81587732 has 6 divisors (see below), whose sum is σ = 142778538. Its totient is φ = 40793864.

The previous prime is 81587731. The next prime is 81587749. The reversal of 81587732 is 23778518.

It can be written as a sum of positive squares in only one way, i.e., 70324996 + 11262736 = 8386^2 + 3356^2 .

It is a self number, because there is not a number n which added to its sum of digits gives 81587732.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81587731) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10198463 + ... + 10198470.

It is an arithmetic number, because the mean of its divisors is an integer number (23796423).

Almost surely, 2^81587732 is an apocalyptic number.

It is an amenable number.

81587732 is a deficient number, since it is larger than the sum of its proper divisors (61190806).

81587732 is a wasteful number, since it uses less digits than its factorization.

81587732 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 20396937 (or 20396935 counting only the distinct ones).

The product of its digits is 94080, while the sum is 41.

The square root of 81587732 is about 9032.5927617711. The cubic root of 81587732 is about 433.7188393209.

The spelling of 81587732 in words is "eighty-one million, five hundred eighty-seven thousand, seven hundred thirty-two".