81587620 has 12 divisors (see below), whose sum is σ = 171334044. Its totient is φ = 32635040.

The previous prime is 81587609. The next prime is 81587633. The reversal of 81587620 is 2678518.

It can be written as a sum of positive squares in 2 ways, for example, as 23736384 + 57851236 = 4872^2 + 7606^2 .

It is a self number, because there is not a number n which added to its sum of digits gives 81587620.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2039671 + ... + 2039710.

It is an arithmetic number, because the mean of its divisors is an integer number (14277837).

Almost surely, 2^81587620 is an apocalyptic number.

It is an amenable number.

81587620 is an abundant number, since it is smaller than the sum of its proper divisors (89746424).

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

81587620 is a wasteful number, since it uses less digits than its factorization.

81587620 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4079390 (or 4079388 counting only the distinct ones).

The product of its (nonzero) digits is 26880, while the sum is 37.

The square root of 81587620 is about 9032.5865619987. The cubic root of 81587620 is about 433.7186408575.

The spelling of 81587620 in words is "eighty-one million, five hundred eighty-seven thousand, six hundred twenty".