81157536 has 36 divisors (see below), whose sum is σ = 230792562. Its totient is φ = 27052416.

The previous prime is 81157529. The next prime is 81157543. The reversal of 81157536 is 63575118.

81157536 is a `hidden beast` number, since 8 + 115 + 7 + 536 = 666.

It is an interprime number because it is at equal distance from previous prime (81157529) and next prime (81157543).

It can be written as a sum of positive squares in only one way, i.e., 73205136 + 7952400 = 8556^2 + 2820^2 .

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 81157536.

It is an unprimeable number.

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 5 ways as a sum of consecutive naturals, for example, 140611 + ... + 141186.

Almost surely, 2^81157536 is an apocalyptic number.

It is an amenable number.

81157536 is an abundant number, since it is smaller than the sum of its proper divisors (149635026).

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

81157536 is a wasteful number, since it uses less digits than its factorization.

81157536 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 281813 (or 281802 counting only the distinct ones).

The product of its digits is 25200, while the sum is 36.

The square root of 81157536 is about 9008.7477487162. The cubic root of 81157536 is about 432.9551909568.

It can be divided in two parts, 8115 and 7536, that added together give a palindrome (15651).

The spelling of 81157536 in words is "eighty-one million, one hundred fifty-seven thousand, five hundred thirty-six".