81938957 has 2 divisors, whose sum is σ = 81938958. Its totient is φ = 81938956.

The previous prime is 81938953. The next prime is 81938981. The reversal of 81938957 is 75983918.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 55785961 + 26152996 = 7469^2 + 5114^2 .

It is a cyclic number.

It is not a de Polignac number, because 81938957 - 2² = 81938953 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (81938953) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40969478 + 40969479.

It is an arithmetic number, because the mean of its divisors is an integer number (40969479).

Almost surely, 2^81938957 is an apocalyptic number.

It is an amenable number.

81938957 is a deficient number, since it is larger than the sum of its proper divisors (1).

81938957 is an equidigital number, since it uses as much as digits as its factorization.

81938957 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 544320, while the sum is 50.

The square root of 81938957 is about 9052.0139748014. The cubic root of 81938957 is about 434.3403168623.

The spelling of 81938957 in words is "eighty-one million, nine hundred thirty-eight thousand, nine hundred fifty-seven".