81572436 has 36 divisors (see below), whose sum is σ = 224943264. Its totient is φ = 24718800.

The previous prime is 81572431. The next prime is 81572461. The reversal of 81572436 is 63427518.

81572436 is a `hidden beast` number, since 81 + 572 + 4 + 3 + 6 = 666.

It is a tau number, because it is divible by the number of its divisors (36).

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

It is a self number, because there is not a number n which added to its sum of digits gives 81572436.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81572431) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 102600 + ... + 103391.

It is an arithmetic number, because the mean of its divisors is an integer number (6248424).

Almost surely, 2^81572436 is an apocalyptic number.

It is an amenable number.

81572436 is an abundant number, since it is smaller than the sum of its proper divisors (143370828).

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

81572436 is a wasteful number, since it uses less digits than its factorization.

81572436 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 206012 (or 206007 counting only the distinct ones).

The product of its digits is 40320, while the sum is 36.

The square root of 81572436 is about 9031.7460106006. The cubic root of 81572436 is about 433.6917332114.

The spelling of 81572436 in words is "eighty-one million, five hundred seventy-two thousand, four hundred thirty-six".