28623921 has 4 divisors (see below), whose sum is σ = 38165232. Its totient is φ = 19082612.

The previous prime is 28623919. The next prime is 28623923. The reversal of 28623921 is 12932682.

It is a happy number.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is an interprime number because it is at equal distance from previous prime (28623919) and next prime (28623923).

It is a cyclic number.

It is not a de Polignac number, because 28623921 - 2¹ = 28623919 is a prime.

It is not an unprimeable number, because it can be changed into a prime (28623923) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 4770651 + ... + 4770656.

It is an arithmetic number, because the mean of its divisors is an integer number (9541308).

Almost surely, 2^28623921 is an apocalyptic number.

It is an amenable number.

28623921 is a deficient number, since it is larger than the sum of its proper divisors (9541311).

28623921 is an equidigital number, since it uses as much as digits as its factorization.

28623921 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9541310.

The product of its digits is 10368, while the sum is 33.

The square root of 28623921 is about 5350.1328020901. The cubic root of 28623921 is about 305.8978149982.

The spelling of 28623921 in words is "twenty-eight million, six hundred twenty-three thousand, nine hundred twenty-one".