81951579 has 24 divisors (see below), whose sum is σ = 127654800. Its totient is φ = 50492160.

The previous prime is 81951557. The next prime is 81951581. The reversal of 81951579 is 97515918.

It is not a de Polignac number, because 81951579 - 2⁵ = 81951547 is a prime.

It is a super-2 number, since 2×81951579² = 13432122601186482, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (81951179) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 1167 + ... + 12855.

It is an arithmetic number, because the mean of its divisors is an integer number (5318950).

Almost surely, 2^81951579 is an apocalyptic number.

81951579 is a deficient number, since it is larger than the sum of its proper divisors (45703221).

81951579 is a wasteful number, since it uses less digits than its factorization.

81951579 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 11755 (or 11752 counting only the distinct ones).

The product of its digits is 113400, while the sum is 45.

The square root of 81951579 is about 9052.7111408682. The cubic root of 81951579 is about 434.3626178621.

The spelling of 81951579 in words is "eighty-one million, nine hundred fifty-one thousand, five hundred seventy-nine".