28021933 has 4 divisors (see below), whose sum is σ = 29670300. Its totient is φ = 26373568.

The previous prime is 28021919. The next prime is 28021943. The reversal of 28021933 is 33912082.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 22155849 + 5866084 = 4707^2 + 2422^2 .

It is a cyclic number.

It is not a de Polignac number, because 28021933 - 2⁹ = 28021421 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (28021943) 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, 824158 + ... + 824191.

It is an arithmetic number, because the mean of its divisors is an integer number (7417575).

Almost surely, 2^28021933 is an apocalyptic number.

It is an amenable number.

28021933 is a deficient number, since it is larger than the sum of its proper divisors (1648367).

28021933 is a wasteful number, since it uses less digits than its factorization.

28021933 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1648366.

The product of its (nonzero) digits is 2592, while the sum is 28.

The square root of 28021933 is about 5293.5746901314. The cubic root of 28021933 is about 303.7381640011.

The spelling of 28021933 in words is "twenty-eight million, twenty-one thousand, nine hundred thirty-three".