81779930 has 16 divisors (see below), whose sum is σ = 149278464. Its totient is φ = 32250960.

The previous prime is 81779921. The next prime is 81779947. The reversal of 81779930 is 3997718.

It is a Curzon number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 56882 + ... + 58301.

It is an arithmetic number, because the mean of its divisors is an integer number (9329904).

Almost surely, 2^81779930 is an apocalyptic number.

81779930 is a deficient number, since it is larger than the sum of its proper divisors (67498534).

81779930 is a wasteful number, since it uses less digits than its factorization.

81779930 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 115261.

The product of its (nonzero) digits is 95256, while the sum is 44.

The square root of 81779930 is about 9043.2256413295. The cubic root of 81779930 is about 434.0591458817.

The spelling of 81779930 in words is "eighty-one million, seven hundred seventy-nine thousand, nine hundred thirty".