27979813 has 4 divisors (see below), whose sum is σ = 28507788. Its totient is φ = 27451840.

The previous prime is 27979771. The next prime is 27979823. The reversal of 27979813 is 31897972.

It is a happy number.

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

It can be written as a sum of positive squares in 2 ways, for example, as 16467364 + 11512449 = 4058^2 + 3393^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-27979813 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (27979823) 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, 263908 + ... + 264013.

It is an arithmetic number, because the mean of its divisors is an integer number (7126947).

Almost surely, 2^27979813 is an apocalyptic number.

It is an amenable number.

27979813 is a deficient number, since it is larger than the sum of its proper divisors (527975).

27979813 is an equidigital number, since it uses as much as digits as its factorization.

27979813 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 527974.

The product of its digits is 190512, while the sum is 46.

The square root of 27979813 is about 5289.5947859926. The cubic root of 27979813 is about 303.5859039029.

The spelling of 27979813 in words is "twenty-seven million, nine hundred seventy-nine thousand, eight hundred thirteen".