21217008 has 40 divisors (see below), whose sum is σ = 56152656. Its totient is φ = 6899200.

The previous prime is 21216997. The next prime is 21217019. The reversal of 21217008 is 80071212.

It is an interprime number because it is at equal distance from previous prime (21216997) and next prime (21217019).

It is a super-2 number, since 2×21217008² = 900322856944128, which contains 22 as substring.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 3423 + ... + 7358.

Almost surely, 2^21217008 is an apocalyptic number.

It is an amenable number.

21217008 is an abundant number, since it is smaller than the sum of its proper divisors (34935648).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21217008 is a wasteful number, since it uses less digits than its factorization.

21217008 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10833 (or 10827 counting only the distinct ones).

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

The square root of 21217008 is about 4606.1923537777. The cubic root of 21217008 is about 276.8394939582.

The spelling of 21217008 in words is "twenty-one million, two hundred seventeen thousand, eight".