20638720 has 88 divisors (see below), whose sum is σ = 51584400. Its totient is φ = 7913472.

The previous prime is 20638699. The next prime is 20638729. The reversal of 20638720 is 2783602.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20638729) 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, 148411 + ... + 148549.

Almost surely, 2^20638720 is an apocalyptic number.

20638720 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 20638720, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (25792200).

20638720 is an abundant number, since it is smaller than the sum of its proper divisors (30945680).

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

20638720 is a wasteful number, since it uses less digits than its factorization.

20638720 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 193 (or 175 counting only the distinct ones).

The product of its (nonzero) digits is 4032, while the sum is 28.

The square root of 20638720 is about 4542.9858023111. The cubic root of 20638720 is about 274.3011234729.

The spelling of 20638720 in words is "twenty million, six hundred thirty-eight thousand, seven hundred twenty".