81913577 has 2 divisors, whose sum is σ = 81913578. Its totient is φ = 81913576.

The previous prime is 81913571. The next prime is 81913583. The reversal of 81913577 is 77531918.

It is a balanced prime because it is at equal distance from previous prime (81913571) and next prime (81913583).

It can be written as a sum of positive squares in only one way, i.e., 78659161 + 3254416 = 8869^2 + 1804^2 .

It is a cyclic number.

It is not a de Polignac number, because 81913577 - 2⁴ = 81913561 is a prime.

It is not a weakly prime, because it can be changed into another prime (81913571) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40956788 + 40956789.

It is an arithmetic number, because the mean of its divisors is an integer number (40956789).

Almost surely, 2^81913577 is an apocalyptic number.

It is an amenable number.

81913577 is a deficient number, since it is larger than the sum of its proper divisors (1).

81913577 is an equidigital number, since it uses as much as digits as its factorization.

81913577 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 52920, while the sum is 41.

The square root of 81913577 is about 9050.6119682594. The cubic root of 81913577 is about 434.2954676395.

The spelling of 81913577 in words is "eighty-one million, nine hundred thirteen thousand, five hundred seventy-seven".