81908586 has 24 divisors (see below), whose sum is σ = 183589380. Its totient is φ = 26361216.

The previous prime is 81908551. The next prime is 81908597. The reversal of 81908586 is 68580918.

It can be written as a sum of positive squares in 2 ways, for example, as 76475025 + 5433561 = 8745^2 + 2331^2 .

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 77935 + ... + 78978.

Almost surely, 2^81908586 is an apocalyptic number.

81908586 is an abundant number, since it is smaller than the sum of its proper divisors (101680794).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

81908586 is a wasteful number, since it uses less digits than its factorization.

81908586 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 156950 (or 156947 counting only the distinct ones).

The product of its (nonzero) digits is 138240, while the sum is 45.

The square root of 81908586 is about 9050.3362368478. The cubic root of 81908586 is about 434.2866469093.

The spelling of 81908586 in words is "eighty-one million, nine hundred eight thousand, five hundred eighty-six".