28691031 has 4 divisors (see below), whose sum is σ = 38254712. Its totient is φ = 19127352.

The previous prime is 28691017. The next prime is 28691059. The reversal of 28691031 is 13019682.

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

It is not a de Polignac number, because 28691031 - 2¹⁰ = 28690007 is a prime.

It is a super-2 number, since 2×28691031² = 1646350519685922, which contains 22 as substring.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 28691031.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (28691071) 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, 4781836 + ... + 4781841.

It is an arithmetic number, because the mean of its divisors is an integer number (9563678).

Almost surely, 2^28691031 is an apocalyptic number.

28691031 is a deficient number, since it is larger than the sum of its proper divisors (9563681).

28691031 is an equidigital number, since it uses as much as digits as its factorization.

28691031 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9563680.

The product of its (nonzero) digits is 2592, while the sum is 30.

The square root of 28691031 is about 5356.4009371965. The cubic root of 28691031 is about 306.1366918882.

The spelling of 28691031 in words is "twenty-eight million, six hundred ninety-one thousand, thirty-one".