28206931 has 4 divisors (see below), whose sum is σ = 29116864. Its totient is φ = 27297000.

The previous prime is 28206907. The next prime is 28206943. The reversal of 28206931 is 13960282.

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

It is a cyclic number.

It is not a de Polignac number, because 28206931 - 2¹³ = 28198739 is a prime.

It is a super-2 number, since 2×28206931² = 1591261912877522, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (31), and also a Moran number because the ratio is a prime number: 909901 = 28206931 / (2 + 8 + 2 + 0 + 6 + 9 + 3 + 1).

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 28206893 and 28206902.

It is not an unprimeable number, because it can be changed into a prime (28206991) 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, 454920 + ... + 454981.

It is an arithmetic number, because the mean of its divisors is an integer number (7279216).

Almost surely, 2^28206931 is an apocalyptic number.

28206931 is a deficient number, since it is larger than the sum of its proper divisors (909933).

28206931 is an equidigital number, since it uses as much as digits as its factorization.

28206931 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 909932.

The product of its (nonzero) digits is 5184, while the sum is 31.

The square root of 28206931 is about 5311.0197702513. The cubic root of 28206931 is about 304.4051147634.

The spelling of 28206931 in words is "twenty-eight million, two hundred six thousand, nine hundred thirty-one".