21587005 has 24 divisors (see below), whose sum is σ = 29417472. Its totient is φ = 15180000.

The previous prime is 21586997. The next prime is 21587017. The reversal of 21587005 is 50078512.

It is not a de Polignac number, because 21587005 - 2³ = 21586997 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, 18180 + ... + 19330.

It is an arithmetic number, because the mean of its divisors is an integer number (1225728).

Almost surely, 2^21587005 is an apocalyptic number.

It is an amenable number.

21587005 is a deficient number, since it is larger than the sum of its proper divisors (7830467).

21587005 is a wasteful number, since it uses less digits than its factorization.

21587005 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1209 (or 1198 counting only the distinct ones).

The product of its (nonzero) digits is 2800, while the sum is 28.

The square root of 21587005 is about 4646.1817657083. The cubic root of 21587005 is about 278.4394693251.

The spelling of 21587005 in words is "twenty-one million, five hundred eighty-seven thousand, five".