81573377 has 2 divisors, whose sum is σ = 81573378. Its totient is φ = 81573376.

The previous prime is 81573367. The next prime is 81573379. The reversal of 81573377 is 77337518.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 52940176 + 28633201 = 7276^2 + 5351^2 .

It is a cyclic number.

It is not a de Polignac number, because 81573377 - 2²² = 77379073 is a prime.

Together with 81573379, it forms a pair of twin primes.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (81573379) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40786688 + 40786689.

It is an arithmetic number, because the mean of its divisors is an integer number (40786689).

Almost surely, 2^81573377 is an apocalyptic number.

It is an amenable number.

81573377 is a deficient number, since it is larger than the sum of its proper divisors (1).

81573377 is an equidigital number, since it uses as much as digits as its factorization.

81573377 is an evil number, because the sum of its binary digits is even.

The product of its digits is 123480, while the sum is 41.

The square root of 81573377 is about 9031.7981044751. The cubic root of 81573377 is about 433.6934008595.

The spelling of 81573377 in words is "eighty-one million, five hundred seventy-three thousand, three hundred seventy-seven".