28021924 has 18 divisors (see below), whose sum is σ = 57045030. Its totient is φ = 12009312.

The previous prime is 28021919. The next prime is 28021943. The reversal of 28021924 is 42912082.

It can be written as a sum of positive squares in only one way, i.e., 16257024 + 11764900 = 4032^2 + 3430^2 .

It is a Harshad number since it is a multiple of its sum of digits (28).

It is a junction number, because it is equal to n+sod(n) for n = 28021892 and 28021901.

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, 71289 + ... + 71680.

Almost surely, 2^28021924 is an apocalyptic number.

It is an amenable number.

28021924 is an abundant number, since it is smaller than the sum of its proper divisors (29023106).

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

28021924 is a wasteful number, since it uses less digits than its factorization.

28021924 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 142987 (or 142978 counting only the distinct ones).

The product of its (nonzero) digits is 2304, while the sum is 28.

The square root of 28021924 is about 5293.5738400442. The cubic root of 28021924 is about 303.7381314832.

The spelling of 28021924 in words is "twenty-eight million, twenty-one thousand, nine hundred twenty-four".