28918931 has 4 divisors (see below), whose sum is σ = 30441000. Its totient is φ = 27396864.

The previous prime is 28918907. The next prime is 28918933. The reversal of 28918931 is 13981982.

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 28918931 - 2¹⁸ = 28656787 is a prime.

It is a super-2 number, since 2×28918931² = 1672609140365522, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (28918933) 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, 761006 + ... + 761043.

It is an arithmetic number, because the mean of its divisors is an integer number (7610250).

Almost surely, 2^28918931 is an apocalyptic number.

28918931 is a deficient number, since it is larger than the sum of its proper divisors (1522069).

28918931 is a wasteful number, since it uses less digits than its factorization.

28918931 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1522068.

The product of its digits is 31104, while the sum is 41.

The square root of 28918931 is about 5377.6324716366. The cubic root of 28918931 is about 306.9451284262.

The spelling of 28918931 in words is "twenty-eight million, nine hundred eighteen thousand, nine hundred thirty-one".