81587538 has 18 divisors (see below), whose sum is σ = 176856069. Its totient is φ = 27183072.

The previous prime is 81587521. The next prime is 81587549. The reversal of 81587538 is 83578518.

It is a happy number.

It can be written as a sum of positive squares in 2 ways, for example, as 76265289 + 5322249 = 8733^2 + 2307^2 .

It is a tau number, because it is divible by the number of its divisors (18).

It is an ABA number since it can be written as A⋅B^A, here for A=2, B=6387.

It is a junction number, because it is equal to n+sod(n) for n = 81587493 and 81587502.

It is an unprimeable number.

It is a polite number, since it can be written in 8 ways as a sum of consecutive naturals, for example, 37258 + ... + 39386.

Almost surely, 2^81587538 is an apocalyptic number.

81587538 is an abundant number, since it is smaller than the sum of its proper divisors (95268531).

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

81587538 is an equidigital number, since it uses as much as digits as its factorization.

81587538 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4266 (or 2134 counting only the distinct ones).

The product of its digits is 268800, while the sum is 45.

The square root of 81587538 is about 9032.5820228770. The cubic root of 81587538 is about 433.7184955539.

The spelling of 81587538 in words is "eighty-one million, five hundred eighty-seven thousand, five hundred thirty-eight".