28372391 has 4 divisors (see below), whose sum is σ = 28383984. Its totient is φ = 28360800.

The previous prime is 28372387. The next prime is 28372397. The reversal of 28372391 is 19327382.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It is a cyclic number.

It is not a de Polignac number, because 28372391 - 2² = 28372387 is a prime.

It is a super-3 number, since 3×28372391³ (a number of 23 digits) contains 333 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (28372397) 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, 530 + ... + 7551.

It is an arithmetic number, because the mean of its divisors is an integer number (7095996).

Almost surely, 2^28372391 is an apocalyptic number.

28372391 is a deficient number, since it is larger than the sum of its proper divisors (11593).

28372391 is an equidigital number, since it uses as much as digits as its factorization.

28372391 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 11592.

The product of its digits is 18144, while the sum is 35.

The square root of 28372391 is about 5326.5740396619. The cubic root of 28372391 is about 304.9991615134. Note that the first 3 decimals are identical.

The spelling of 28372391 in words is "twenty-eight million, three hundred seventy-two thousand, three hundred ninety-one".