20907990 has 64 divisors (see below), whose sum is σ = 56171520. Its totient is φ = 5533920.

The previous prime is 20907983. The next prime is 20908001. The reversal of 20907990 is 9970902.

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

It is a congruent number.

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, 56787 + ... + 57153.

It is an arithmetic number, because the mean of its divisors is an integer number (877680).

Almost surely, 2^20907990 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 20907990, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (28085760).

20907990 is an abundant number, since it is smaller than the sum of its proper divisors (35263530).

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

20907990 is a wasteful number, since it uses less digits than its factorization.

20907990 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 594 (or 588 counting only the distinct ones).

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

The square root of 20907990 is about 4572.5255603441. The cubic root of 20907990 is about 275.4888934184.

The spelling of 20907990 in words is "twenty million, nine hundred seven thousand, nine hundred ninety".