# 81

9

5

121

## Factorization

81 = 3 × 3 × 3 × 3

Factor Count
3 4

6561

531441

9

## Cube root of 81

4.32674871092222446122832479886711...

3321

## Reciprocal of 81

0.0123456790123457

1010001

7

## Octal of 81

121

51

 Prime number No Hexagonal number No Perfect number No Deficient number No Abundant number No Mersenne number No Harshad number Yes Harmonic divisor number No

QR81 (sequence)

111

54

54

0

## Properties of 81

Properties of the number 81: 81 has 5 divisors. The divisors of 81 are 1, 3, 9, 27, 81 and the sum of them is 121. The factorization of 81 is 3 × 3 × 3 × 3. The square and cube of 81 are 6561 and 531441 respectively. The square root and cube root of 81 are 9 and 4.32674871092222446122832479886711.... The binary, octal, hexadecimal of 81 are 1010001, 121, 51. 81 is not a prime number, not hexagonal number, not perfect number, not deficient number, not Mersenne number, not Mersenne number, Harshad number, not harmonic divisor number.

## sin 81

-0.62988799427445385514801046156208...

## cos 81

0.77668598202163119381680189690087...

## tan 81

-0.81099441583189424420652358094230...

## sin 81°

0.98768834059513777035022030759137...

## cos 81°

0.15643446504023092447077658562193...

## tan 81°

6.31375151467504114322082386934198...

## log 81

4.39444915467243912843287034775130...

## log10 81

1.90848501887864974158048880781280...

## log2 81

6.33985000288462430262370617128909...