21790902 has 16 divisors (see below), whose sum is σ = 49807872. Its totient is φ = 6225960.

The previous prime is 21790843. The next prime is 21790921. The reversal of 21790902 is 20909712.

It is a self number, because there is not a number n which added to its sum of digits gives 21790902.

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, 259374 + ... + 259457.

It is an arithmetic number, because the mean of its divisors is an integer number (3112992).

Almost surely, 2^21790902 is an apocalyptic number.

21790902 is an abundant number, since it is smaller than the sum of its proper divisors (28016970).

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

21790902 is a wasteful number, since it uses less digits than its factorization.

21790902 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 518843.

The product of its (nonzero) digits is 2268, while the sum is 30.

The square root of 21790902 is about 4668.0726215431. The cubic root of 21790902 is about 279.3133771468.

It can be divided in two parts, 217 and 90902, that added together give a palindrome (91119).

The spelling of 21790902 in words is "twenty-one million, seven hundred ninety thousand, nine hundred two".