87810921 has 12 divisors (see below), whose sum is σ = 138368880. Its totient is φ = 53218680.

The previous prime is 87810911. The next prime is 87810959. The reversal of 87810921 is 12901878.

It is not a de Polignac number, because 87810921 - 2⁶ = 87810857 is a prime.

It is an alternating number because its digits alternate between even and odd.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (87810911) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 443391 + ... + 443588.

It is an arithmetic number, because the mean of its divisors is an integer number (11530740).

Almost surely, 2^87810921 is an apocalyptic number.

It is an amenable number.

87810921 is a deficient number, since it is larger than the sum of its proper divisors (50557959).

87810921 is a wasteful number, since it uses less digits than its factorization.

87810921 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 886996 (or 886993 counting only the distinct ones).

The product of its (nonzero) digits is 8064, while the sum is 36.

The square root of 87810921 is about 9370.7481558305. The cubic root of 87810921 is about 444.4772230663.

The spelling of 87810921 in words is "eighty-seven million, eight hundred ten thousand, nine hundred twenty-one".