20997090 has 64 divisors (see below), whose sum is σ = 58953600. Its totient is φ = 5303232.

The previous prime is 20997059. The next prime is 20997101. The reversal of 20997090 is 9079902.

It is a hoax number, since the sum of its digits (36) coincides with the sum of the digits of its distinct prime factors.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 3084 + ... + 7176.

It is an arithmetic number, because the mean of its divisors is an integer number (921150).

Almost surely, 2^20997090 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 20997090, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (29476800).

20997090 is an abundant number, since it is smaller than the sum of its proper divisors (37956510).

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

20997090 is a wasteful number, since it uses less digits than its factorization.

20997090 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4128 (or 4122 counting only the distinct ones).

The product of its (nonzero) digits is 10206, while the sum is 36.

The square root of 20997090 is about 4582.2581769254. The cubic root of 20997090 is about 275.8796734473.

The spelling of 20997090 in words is "twenty million, nine hundred ninety-seven thousand, ninety".