21587859 has 12 divisors (see below), whose sum is σ = 31459896. Its totient is φ = 14263872.

The previous prime is 21587837. The next prime is 21587879. The reversal of 21587859 is 95878512.

It is a happy number.

It is not a de Polignac number, because 21587859 - 2⁵ = 21587827 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21587809) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 9597 + ... + 11630.

It is an arithmetic number, because the mean of its divisors is an integer number (2621658).

Almost surely, 2^21587859 is an apocalyptic number.

21587859 is a deficient number, since it is larger than the sum of its proper divisors (9872037).

21587859 is a wasteful number, since it uses less digits than its factorization.

21587859 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 21346 (or 21343 counting only the distinct ones).

The product of its digits is 201600, while the sum is 45.

The square root of 21587859 is about 4646.2736682206. The cubic root of 21587859 is about 278.4431410429.

The spelling of 21587859 in words is "twenty-one million, five hundred eighty-seven thousand, eight hundred fifty-nine".