20724990 has 64 divisors (see below), whose sum is σ = 58447872. Its totient is φ = 4636800.

The previous prime is 20724973. The next prime is 20725007. The reversal of 20724990 is 9942702.

It is an interprime number because it is at equal distance from previous prime (20724973) and next prime (20725007).

It is a Harshad number since it is a multiple of its sum of digits (33).

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, 1875 + ... + 6705.

It is an arithmetic number, because the mean of its divisors is an integer number (913248).

Almost surely, 2^20724990 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 20724990, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (29223936).

20724990 is an abundant number, since it is smaller than the sum of its proper divisors (37722882).

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

20724990 is a wasteful number, since it uses less digits than its factorization.

20724990 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4865.

The product of its (nonzero) digits is 9072, while the sum is 33.

The square root of 20724990 is about 4552.4707577315. The cubic root of 20724990 is about 274.6827857472.

The spelling of 20724990 in words is "twenty million, seven hundred twenty-four thousand, nine hundred ninety".