21170808 has 80 divisors (see below), whose sum is σ = 60969480. Its totient is φ = 6858432.

The previous prime is 21170789. The next prime is 21170857. The reversal of 21170808 is 80807112.

It is a super-2 number, since 2×21170808² = 896406222745728, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 19 ways as a sum of consecutive naturals, for example, 23535 + ... + 24417.

Almost surely, 2^21170808 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21170808, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (30484740).

21170808 is an abundant number, since it is smaller than the sum of its proper divisors (39798672).

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

21170808 is a wasteful number, since it uses less digits than its factorization.

21170808 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 938 (or 925 counting only the distinct ones).

The product of its (nonzero) digits is 896, while the sum is 27.

The square root of 21170808 is about 4601.1746326346. The cubic root of 21170808 is about 276.6384087524.

The spelling of 21170808 in words is "twenty-one million, one hundred seventy thousand, eight hundred eight".