81231737 has 2 divisors, whose sum is σ = 81231738. Its totient is φ = 81231736.

The previous prime is 81231679. The next prime is 81231743. The reversal of 81231737 is 73713218.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 74580496 + 6651241 = 8636^2 + 2579^2 .

It is a cyclic number.

It is not a de Polignac number, because 81231737 - 2⁶ = 81231673 is a prime.

It is not a weakly prime, because it can be changed into another prime (81231757) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40615868 + 40615869.

It is an arithmetic number, because the mean of its divisors is an integer number (40615869).

Almost surely, 2^81231737 is an apocalyptic number.

It is an amenable number.

81231737 is a deficient number, since it is larger than the sum of its proper divisors (1).

81231737 is an equidigital number, since it uses as much as digits as its factorization.

81231737 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 7056, while the sum is 32.

The square root of 81231737 is about 9012.8650827581. The cubic root of 81231737 is about 433.0870987007.

The spelling of 81231737 in words is "eighty-one million, two hundred thirty-one thousand, seven hundred thirty-seven".