81587975 has 24 divisors (see below), whose sum is σ = 116563968. Its totient is φ = 55490400.

The previous prime is 81587963. The next prime is 81587983. The reversal of 81587975 is 57978518.

It is not a de Polignac number, because 81587975 - 2⁴ = 81587959 is a prime.

It is a Duffinian number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 20390 + ... + 24060.

It is an arithmetic number, because the mean of its divisors is an integer number (4856832).

Almost surely, 2^81587975 is an apocalyptic number.

81587975 is a deficient number, since it is larger than the sum of its proper divisors (34975993).

81587975 is a wasteful number, since it uses less digits than its factorization.

81587975 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3815 (or 3810 counting only the distinct ones).

The product of its digits is 705600, while the sum is 50.

The square root of 81587975 is about 9032.6062130484. The cubic root of 81587975 is about 433.7192699150.

The spelling of 81587975 in words is "eighty-one million, five hundred eighty-seven thousand, nine hundred seventy-five".