21087008 has 12 divisors (see below), whose sum is σ = 41515110. Its totient is φ = 10543488.

The previous prime is 21086981. The next prime is 21087019. The reversal of 21087008 is 80078012.

It can be written as a sum of positive squares in only one way, i.e., 15460624 + 5626384 = 3932^2 + 2372^2 .

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 329453 + ... + 329516.

Almost surely, 2^21087008 is an apocalyptic number.

It is an amenable number.

21087008 is a deficient number, since it is larger than the sum of its proper divisors (20428102).

21087008 is an equidigital number, since it uses as much as digits as its factorization.

21087008 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 658979 (or 658971 counting only the distinct ones).

The product of its (nonzero) digits is 896, while the sum is 26.

The square root of 21087008 is about 4592.0592330674. The cubic root of 21087008 is about 276.2729219393.

The spelling of 21087008 in words is "twenty-one million, eighty-seven thousand, eight".