81906764 has 12 divisors (see below), whose sum is σ = 143483088. Its totient is φ = 40911600.

The previous prime is 81906719. The next prime is 81906823. The reversal of 81906764 is 46760918.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 5807 + ... + 14054.

It is an arithmetic number, because the mean of its divisors is an integer number (11956924).

Almost surely, 2^81906764 is an apocalyptic number.

It is an amenable number.

81906764 is a deficient number, since it is larger than the sum of its proper divisors (61576324).

81906764 is a wasteful number, since it uses less digits than its factorization.

81906764 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 20896 (or 20894 counting only the distinct ones).

The product of its (nonzero) digits is 72576, while the sum is 41.

The square root of 81906764 is about 9050.2355770444. The cubic root of 81906764 is about 434.2834267498.

The spelling of 81906764 in words is "eighty-one million, nine hundred six thousand, seven hundred sixty-four".