81359731 has 2 divisors, whose sum is σ = 81359732. Its totient is φ = 81359730.

The previous prime is 81359711. The next prime is 81359737. The reversal of 81359731 is 13795318.

It is a happy number.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 81359731 - 2⁵ = 81359699 is a prime.

It is a super-2 number, since 2×81359731² = 13238811656784722, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (81359737) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40679865 + 40679866.

It is an arithmetic number, because the mean of its divisors is an integer number (40679866).

Almost surely, 2^81359731 is an apocalyptic number.

81359731 is a deficient number, since it is larger than the sum of its proper divisors (1).

81359731 is an equidigital number, since it uses as much as digits as its factorization.

81359731 is an evil number, because the sum of its binary digits is even.

The product of its digits is 22680, while the sum is 37.

The square root of 81359731 is about 9019.9629156666. The cubic root of 81359731 is about 433.3144460538.

The spelling of 81359731 in words is "eighty-one million, three hundred fifty-nine thousand, seven hundred thirty-one".