21079013 has 4 divisors (see below), whose sum is σ = 21141900. Its totient is φ = 21016128.

The previous prime is 21079007. The next prime is 21079021. The reversal of 21079013 is 31097012.

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 15499969 + 5579044 = 3937^2 + 2362^2 .

It is a cyclic number.

It is not a de Polignac number, because 21079013 - 2⁶ = 21078949 is a prime.

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 21079013.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21079313) 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, 30938 + ... + 31611.

It is an arithmetic number, because the mean of its divisors is an integer number (5285475).

Almost surely, 2^21079013 is an apocalyptic number.

It is an amenable number.

21079013 is a deficient number, since it is larger than the sum of its proper divisors (62887).

21079013 is an equidigital number, since it uses as much as digits as its factorization.

21079013 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 62886.

The product of its (nonzero) digits is 378, while the sum is 23.

The square root of 21079013 is about 4591.1886260532. The cubic root of 21079013 is about 276.2380018403.

The spelling of 21079013 in words is "twenty-one million, seventy-nine thousand, thirteen".