81164651 has 2 divisors, whose sum is σ = 81164652. Its totient is φ = 81164650.

The previous prime is 81164617. The next prime is 81164659. The reversal of 81164651 is 15646118.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 81164651 - 2²² = 76970347 is a prime.

It is a Sophie Germain prime.

It is a Chen prime.

It is equal to p_4733591 and since 81164651 and 4733591 have the same sum of digits, it is a Honaker prime.

It is not a weakly prime, because it can be changed into another prime (81164659) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40582325 + 40582326.

It is an arithmetic number, because the mean of its divisors is an integer number (40582326).

Almost surely, 2^81164651 is an apocalyptic number.

81164651 is a deficient number, since it is larger than the sum of its proper divisors (1).

81164651 is an equidigital number, since it uses as much as digits as its factorization.

81164651 is an evil number, because the sum of its binary digits is even.

The product of its digits is 5760, while the sum is 32.

The square root of 81164651 is about 9009.1426340135. The cubic root of 81164651 is about 432.9678428366.

The spelling of 81164651 in words is "eighty-one million, one hundred sixty-four thousand, six hundred fifty-one".