21790808 has 32 divisors (see below), whose sum is σ = 44271360. Its totient is φ = 9995520.

The previous prime is 21790801. The next prime is 21790841. The reversal of 21790808 is 80809712.

It is a happy number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21790801) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 19316 + ... + 20412.

It is an arithmetic number, because the mean of its divisors is an integer number (1383480).

Almost surely, 2^21790808 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 21790808, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (22135680).

21790808 is an abundant number, since it is smaller than the sum of its proper divisors (22480552).

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

21790808 is a wasteful number, since it uses less digits than its factorization.

21790808 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1307 (or 1303 counting only the distinct ones).

The product of its (nonzero) digits is 8064, while the sum is 35.

The square root of 21790808 is about 4668.0625531370. The cubic root of 21790808 is about 279.3129755190.

The spelling of 21790808 in words is "twenty-one million, seven hundred ninety thousand, eight hundred eight".