81956957 has 2 divisors, whose sum is σ = 81956958. Its totient is φ = 81956956.

The previous prime is 81956923. The next prime is 81956989. The reversal of 81956957 is 75965918.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 60621796 + 21335161 = 7786^2 + 4619^2 .

It is a cyclic number.

It is not a de Polignac number, because 81956957 - 2⁶ = 81956893 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (81956057) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40978478 + 40978479.

It is an arithmetic number, because the mean of its divisors is an integer number (40978479).

Almost surely, 2^81956957 is an apocalyptic number.

It is an amenable number.

81956957 is a deficient number, since it is larger than the sum of its proper divisors (1).

81956957 is an equidigital number, since it uses as much as digits as its factorization.

81956957 is an evil number, because the sum of its binary digits is even.

The product of its digits is 680400, while the sum is 50.

The square root of 81956957 is about 9053.0081740822. The cubic root of 81956957 is about 434.3721192087.

The spelling of 81956957 in words is "eighty-one million, nine hundred fifty-six thousand, nine hundred fifty-seven".