28131920 has 30 divisors (see below), whose sum is σ = 65517198. Its totient is φ = 11233792.

The previous prime is 28131907. The next prime is 28131931. The reversal of 28131920 is 2913182.

It can be written as a sum of positive squares in 3 ways, for example, as 5053504 + 23078416 = 2248^2 + 4804^2 .

It is a self number, because there is not a number n which added to its sum of digits gives 28131920.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 47144 + ... + 47736.

Almost surely, 2^28131920 is an apocalyptic number.

28131920 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

28131920 is an abundant number, since it is smaller than the sum of its proper divisors (37385278).

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

28131920 is an frugal number, since it uses more digits than its factorization.

28131920 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1199 (or 600 counting only the distinct ones).

The product of its (nonzero) digits is 864, while the sum is 26.

The square root of 28131920 is about 5303.9532426295. The cubic root of 28131920 is about 304.1350392669.

The spelling of 28131920 in words is "twenty-eight million, one hundred thirty-one thousand, nine hundred twenty".