81604404 has 54 divisors (see below), whose sum is σ = 239960994. Its totient is φ = 23315040.

The previous prime is 81604357. The next prime is 81604423. The reversal of 81604404 is 40440618.

It can be written as a sum of positive squares in only one way, i.e., 81540900 + 63504 = 9030^2 + 252^2 .

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 17 ways as a sum of consecutive naturals, for example, 21367 + ... + 24894.

Almost surely, 2^81604404 is an apocalyptic number.

81604404 is a gapful number since it is divisible by the number (84) formed by its first and last digit.

It is an amenable number.

81604404 is an abundant number, since it is smaller than the sum of its proper divisors (158356590).

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

81604404 is a wasteful number, since it uses less digits than its factorization.

81604404 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 46285 (or 46273 counting only the distinct ones).

The product of its (nonzero) digits is 3072, while the sum is 27.

The square root of 81604404 is about 9033.5155947173. The cubic root of 81604404 is about 433.7483799877.

The spelling of 81604404 in words is "eighty-one million, six hundred four thousand, four hundred four".