81959513 has 2 divisors, whose sum is σ = 81959514. Its totient is φ = 81959512.

The previous prime is 81959503. The next prime is 81959569. The reversal of 81959513 is 31595918.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 81956809 + 2704 = 9053^2 + 52^2 .

It is a cyclic number.

It is not a de Polignac number, because 81959513 - 2²⁴ = 65182297 is a prime.

It is equal to p_4777187 and since 81959513 and 4777187 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 (81959503) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40979756 + 40979757.

It is an arithmetic number, because the mean of its divisors is an integer number (40979757).

Almost surely, 2^81959513 is an apocalyptic number.

It is an amenable number.

81959513 is a deficient number, since it is larger than the sum of its proper divisors (1).

81959513 is an equidigital number, since it uses as much as digits as its factorization.

81959513 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 48600, while the sum is 41.

The square root of 81959513 is about 9053.1493415275. The cubic root of 81959513 is about 434.3766347643.

The spelling of 81959513 in words is "eighty-one million, nine hundred fifty-nine thousand, five hundred thirteen".