81929788 has 12 divisors (see below), whose sum is σ = 144004840. Its totient is φ = 40785552.

The previous prime is 81929777. The next prime is 81929821. The reversal of 81929788 is 88792918.

It is a congruent number.

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, 43806 + ... + 45637.

Almost surely, 2^81929788 is an apocalyptic number.

It is an amenable number.

81929788 is a deficient number, since it is larger than the sum of its proper divisors (62075052).

81929788 is a wasteful number, since it uses less digits than its factorization.

81929788 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 89676 (or 89674 counting only the distinct ones).

The product of its digits is 580608, while the sum is 52.

The square root of 81929788 is about 9051.5074987540. The cubic root of 81929788 is about 434.3241153098.

The spelling of 81929788 in words is "eighty-one million, nine hundred twenty-nine thousand, seven hundred eighty-eight".