21245808 has 40 divisors (see below), whose sum is σ = 55384848. Its totient is φ = 7017472.

The previous prime is 21245803. The next prime is 21245839. The reversal of 21245808 is 80854212.

It is a hoax number, since the sum of its digits (30) coincides with the sum of the digits of its distinct prime factors.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21245803) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 3466 + ... + 7382.

Almost surely, 2^21245808 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 21245808, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (27692424).

21245808 is an abundant number, since it is smaller than the sum of its proper divisors (34139040).

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

21245808 is a wasteful number, since it uses less digits than its factorization.

21245808 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4041 (or 4035 counting only the distinct ones).

The product of its (nonzero) digits is 5120, while the sum is 30.

The square root of 21245808 is about 4609.3175199806. The cubic root of 21245808 is about 276.9646981125.

The spelling of 21245808 in words is "twenty-one million, two hundred forty-five thousand, eight hundred eight".