20999872 has 56 divisors (see below), whose sum is σ = 43781472. Its totient is φ = 9984000.

The previous prime is 20999843. The next prime is 20999887. The reversal of 20999872 is 27899902.

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, 138997 + ... + 139147.

It is an arithmetic number, because the mean of its divisors is an integer number (781812).

Almost surely, 2^20999872 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 20999872, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (21890736).

20999872 is an abundant number, since it is smaller than the sum of its proper divisors (22781600).

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

20999872 is a wasteful number, since it uses less digits than its factorization.

20999872 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 257 (or 247 counting only the distinct ones).

The product of its (nonzero) digits is 163296, while the sum is 46.

The square root of 20999872 is about 4582.5617289896. The cubic root of 20999872 is about 275.8918570936.

The spelling of 20999872 in words is "twenty million, nine hundred ninety-nine thousand, eight hundred seventy-two".