87639817 has 4 divisors (see below), whose sum is σ = 87683860. Its totient is φ = 87595776.

The previous prime is 87639809. The next prime is 87639823. The reversal of 87639817 is 71893678.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 56235001 + 31404816 = 7499^2 + 5604^2 .

It is a cyclic number.

It is not a de Polignac number, because 87639817 - 2³ = 87639809 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (87639847) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 18888 + ... + 23065.

It is an arithmetic number, because the mean of its divisors is an integer number (21920965).

Almost surely, 2^87639817 is an apocalyptic number.

It is an amenable number.

87639817 is a deficient number, since it is larger than the sum of its proper divisors (44043).

87639817 is a wasteful number, since it uses less digits than its factorization.

87639817 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 44042.

The product of its digits is 508032, while the sum is 49.

The square root of 87639817 is about 9361.6140168242. The cubic root of 87639817 is about 444.1883399357.

The spelling of 87639817 in words is "eighty-seven million, six hundred thirty-nine thousand, eight hundred seventeen".