20990720 has 108 divisors (see below), whose sum is σ = 54255936. Its totient is φ = 7772160.

The previous prime is 20990707. The next prime is 20990759. The reversal of 20990720 is 2709902.

It is a happy number.

It is a super-2 number, since 2×20990720² = 881220652236800, which contains 22 as substring.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 677105 + ... + 677135.

Almost surely, 2^20990720 is an apocalyptic number.

20990720 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 20990720, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (27127968).

20990720 is an abundant number, since it is smaller than the sum of its proper divisors (33265216).

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

20990720 is an equidigital number, since it uses as much as digits as its factorization.

20990720 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 98 (or 61 counting only the distinct ones).

The product of its (nonzero) digits is 2268, while the sum is 29.

The square root of 20990720 is about 4581.5630520599. The cubic root of 20990720 is about 275.8517722594.

The spelling of 20990720 in words is "twenty million, nine hundred ninety thousand, seven hundred twenty".