81572904 has 192 divisors, whose sum is σ = 273162240. Its totient is φ = 21479040.

The previous prime is 81572893. The next prime is 81572917. The reversal of 81572904 is 40927518.

81572904 is a `hidden beast` number, since 81 + 572 + 9 + 0 + 4 = 666.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is an unprimeable number.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 359239 + ... + 359465.

It is an arithmetic number, because the mean of its divisors is an integer number (1422720).

Almost surely, 2^81572904 is an apocalyptic number.

81572904 is a gapful number since it is divisible by the number (84) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 81572904, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (136581120).

81572904 is an abundant number, since it is smaller than the sum of its proper divisors (191589336).

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

81572904 is a wasteful number, since it uses less digits than its factorization.

81572904 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 300 (or 293 counting only the distinct ones).

The product of its (nonzero) digits is 20160, while the sum is 36.

The square root of 81572904 is about 9031.7719191751. The cubic root of 81572904 is about 433.6925626065.

It can be divided in two parts, 81 and 572904, that added together give a triangular number (572985 = T₁₀₇₀).

The spelling of 81572904 in words is "eighty-one million, five hundred seventy-two thousand, nine hundred four".