81779530 has 96 divisors (see below), whose sum is σ = 180838656. Its totient is φ = 26522496.

The previous prime is 81779527. The next prime is 81779561. The reversal of 81779530 is 3597718.

81779530 = 469² + 470² + ... + 703².

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 1220557 + ... + 1220623.

It is an arithmetic number, because the mean of its divisors is an integer number (1883736).

Almost surely, 2^81779530 is an apocalyptic number.

81779530 is an abundant number, since it is smaller than the sum of its proper divisors (99059126).

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

81779530 is a wasteful number, since it uses less digits than its factorization.

81779530 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 188 (or 181 counting only the distinct ones).

The product of its (nonzero) digits is 52920, while the sum is 40.

The square root of 81779530 is about 9043.2035253001. The cubic root of 81779530 is about 434.0584381941.

The spelling of 81779530 in words is "eighty-one million, seven hundred seventy-nine thousand, five hundred thirty".