20639872 has 64 divisors (see below), whose sum is σ = 45606240. Its totient is φ = 9226240.

The previous prime is 20639869. The next prime is 20639881. The reversal of 20639872 is 27893602.

20639872 = T₂₄₃ + T₂₄₄ + ... + T₅₁₆.

It is a tau number, because it is divible by the number of its divisors (64).

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 150588 + ... + 150724.

Almost surely, 2^20639872 is an apocalyptic number.

20639872 is a gapful number since it is divisible by the number (22) 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 20639872, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (22803120).

20639872 is an abundant number, since it is smaller than the sum of its proper divisors (24966368).

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

20639872 is a wasteful number, since it uses less digits than its factorization.

20639872 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 269 (or 257 counting only the distinct ones).

The product of its (nonzero) digits is 36288, while the sum is 37.

The square root of 20639872 is about 4543.1125894039. The cubic root of 20639872 is about 274.3062269712.

It can be divided in two parts, 2063 and 9872, that added together give a triangular number (11935 = T₁₅₄).

The spelling of 20639872 in words is "twenty million, six hundred thirty-nine thousand, eight hundred seventy-two".