87210021 has 4 divisors (see below), whose sum is σ = 116280032. Its totient is φ = 58140012.

The previous prime is 87210007. The next prime is 87210023. The reversal of 87210021 is 12001278.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is not a de Polignac number, because 87210021 - 2⁷ = 87209893 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 87210021.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (87210023) 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, 14535001 + ... + 14535006.

It is an arithmetic number, because the mean of its divisors is an integer number (29070008).

Almost surely, 2^87210021 is an apocalyptic number.

It is an amenable number.

87210021 is a deficient number, since it is larger than the sum of its proper divisors (29070011).

87210021 is a wasteful number, since it uses less digits than its factorization.

87210021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 29070010.

The product of its (nonzero) digits is 224, while the sum is 21.

The square root of 87210021 is about 9338.6305741260. The cubic root of 87210021 is about 443.4610323652.

Adding to 87210021 its reverse (12001278), we get a palindrome (99211299).

The spelling of 87210021 in words is "eighty-seven million, two hundred ten thousand, twenty-one".