20728992 has 24 divisors (see below), whose sum is σ = 54413856. Its totient is φ = 6909632.

The previous prime is 20728969. The next prime is 20728993. The reversal of 20728992 is 29982702.

It is a tau number, because it is divible by the number of its divisors (24).

It is a super-2 number, since 2×20728992² = 859382218672128, which contains 22 as substring.

It is a Smith number, since the sum of its digits (39) coincides with the sum of the digits of its prime factors.

It is a self number, because there is not a number n which added to its sum of digits gives 20728992.

It is not an unprimeable number, because it can be changed into a prime (20728993) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 107868 + ... + 108059.

It is an arithmetic number, because the mean of its divisors is an integer number (2267244).

Almost surely, 2^20728992 is an apocalyptic number.

It is an amenable number.

20728992 is an abundant number, since it is smaller than the sum of its proper divisors (33684864).

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

20728992 is a wasteful number, since it uses less digits than its factorization.

20728992 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 215940 (or 215932 counting only the distinct ones).

The product of its (nonzero) digits is 36288, while the sum is 39.

The square root of 20728992 is about 4552.9102780529. The cubic root of 20728992 is about 274.7004650442.

The spelling of 20728992 in words is "twenty million, seven hundred twenty-eight thousand, nine hundred ninety-two".