21990336 has 56 divisors (see below), whose sum is σ = 59307984. Its totient is φ = 7188480.

The previous prime is 21990259. The next prime is 21990337. The reversal of 21990336 is 63309912.

It is a Smith number, since the sum of its digits (33) coincides with the sum of the digits of its prime factors.

It is a junction number, because it is equal to n+sod(n) for n = 21990297 and 21990306.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21990337) 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, 9096 + ... + 11256.

Almost surely, 2^21990336 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 21990336, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (29653992).

21990336 is an abundant number, since it is smaller than the sum of its proper divisors (37317648).

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

21990336 is a wasteful number, since it uses less digits than its factorization.

21990336 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2229 (or 2219 counting only the distinct ones).

The product of its (nonzero) digits is 8748, while the sum is 33.

The square root of 21990336 is about 4689.3854608040. The cubic root of 21990336 is about 280.1628984079.

The spelling of 21990336 in words is "twenty-one million, nine hundred ninety thousand, three hundred thirty-six".