28342921 has 4 divisors (see below), whose sum is σ = 28397844. Its totient is φ = 28288000.

The previous prime is 28342903. The next prime is 28342933. The reversal of 28342921 is 12924382.

28342921 = 3764² + 3765².

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 14175225 + 14167696 = 3765^2 + 3764^2 .

It is a cyclic number.

It is not a de Polignac number, because 28342921 - 2⁷ = 28342793 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (28342901) 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, 26680 + ... + 27721.

It is an arithmetic number, because the mean of its divisors is an integer number (7099461).

Almost surely, 2^28342921 is an apocalyptic number.

28342921 is the 3765-th centered square number.

It is an amenable number.

28342921 is a deficient number, since it is larger than the sum of its proper divisors (54923).

28342921 is an equidigital number, since it uses as much as digits as its factorization.

28342921 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 54922.

The product of its digits is 6912, while the sum is 31.

The square root of 28342921 is about 5323.8070025124. The cubic root of 28342921 is about 304.8935254968.

The spelling of 28342921 in words is "twenty-eight million, three hundred forty-two thousand, nine hundred twenty-one".