28815431 has 4 divisors (see below), whose sum is σ = 28826232. Its totient is φ = 28804632.

The previous prime is 28815407. The next prime is 28815443. The reversal of 28815431 is 13451882.

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 a de Polignac number, because none of the positive numbers 2^k-28815431 is a prime.

It is a super-2 number, since 2×28815431² = 1660658127431522, which contains 22 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 (28815491) 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, 1820 + ... + 7806.

It is an arithmetic number, because the mean of its divisors is an integer number (7206558).

Almost surely, 2^28815431 is an apocalyptic number.

28815431 is a deficient number, since it is larger than the sum of its proper divisors (10801).

28815431 is an equidigital number, since it uses as much as digits as its factorization.

28815431 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10800.

The product of its digits is 7680, while the sum is 32.

The square root of 28815431 is about 5368.0006520119. Note that the first 3 decimals coincide. The cubic root of 28815431 is about 306.5785081868.

The spelling of 28815431 in words is "twenty-eight million, eight hundred fifteen thousand, four hundred thirty-one".