20987172 has 72 divisors (see below), whose sum is σ = 56871360. Its totient is φ = 6505920.

The previous prime is 20987171. The next prime is 20987189. The reversal of 20987172 is 27178902.

It is a super-2 number, since 2×20987172² = 880922777115168, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is not an unprimeable number, because it can be changed into a prime (20987171) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 41473 + ... + 41975.

It is an arithmetic number, because the mean of its divisors is an integer number (789880).

Almost surely, 2^20987172 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 20987172, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (28435680).

20987172 is an abundant number, since it is smaller than the sum of its proper divisors (35884188).

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

20987172 is a wasteful number, since it uses less digits than its factorization.

20987172 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 593 (or 588 counting only the distinct ones).

The product of its (nonzero) digits is 14112, while the sum is 36.

The square root of 20987172 is about 4581.1758315961. The cubic root of 20987172 is about 275.8362292442.

The spelling of 20987172 in words is "twenty million, nine hundred eighty-seven thousand, one hundred seventy-two".