28920720 has 40 divisors (see below), whose sum is σ = 89654976. Its totient is φ = 7712128.

The previous prime is 28920719. The next prime is 28920761. The reversal of 28920720 is 2702982.

It is a tau number, because it is divible by the number of its divisors (40).

It is a Harshad number since it is a multiple of its sum of digits (30).

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, 60012 + ... + 60491.

Almost surely, 2^28920720 is an apocalyptic number.

28920720 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

28920720 is an abundant number, since it is smaller than the sum of its proper divisors (60734256).

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

28920720 is a wasteful number, since it uses less digits than its factorization.

28920720 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 120519 (or 120513 counting only the distinct ones).

The product of its (nonzero) digits is 4032, while the sum is 30.

The square root of 28920720 is about 5377.7988062031. The cubic root of 28920720 is about 306.9514577694.

The spelling of 28920720 in words is "twenty-eight million, nine hundred twenty thousand, seven hundred twenty".