21379013 has 4 divisors (see below), whose sum is σ = 22636620. Its totient is φ = 20121408.

The previous prime is 21378997. The next prime is 21379019. The reversal of 21379013 is 31097312.

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 17123044 + 4255969 = 4138^2 + 2063^2 .

It is a cyclic number.

It is not a de Polignac number, because 21379013 - 2⁴ = 21378997 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 (21379019) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 628778 + ... + 628811.

It is an arithmetic number, because the mean of its divisors is an integer number (5659155).

Almost surely, 2^21379013 is an apocalyptic number.

It is an amenable number.

21379013 is a deficient number, since it is larger than the sum of its proper divisors (1257607).

21379013 is a wasteful number, since it uses less digits than its factorization.

21379013 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1257606.

The product of its (nonzero) digits is 1134, while the sum is 26.

The square root of 21379013 is about 4623.7444782341. The cubic root of 21379013 is about 277.5423218193.

The spelling of 21379013 in words is "twenty-one million, three hundred seventy-nine thousand, thirteen".