21739313 has 4 divisors (see below), whose sum is σ = 22326900. Its totient is φ = 21151728.

The previous prime is 21739309. The next prime is 21739321. The reversal of 21739313 is 31393712.

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 8248384 + 13490929 = 2872^2 + 3673^2 .

It is a cyclic number.

It is not a de Polignac number, because 21739313 - 2² = 21739309 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21739303) 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, 293738 + ... + 293811.

It is an arithmetic number, because the mean of its divisors is an integer number (5581725).

Almost surely, 2^21739313 is an apocalyptic number.

It is an amenable number.

21739313 is a deficient number, since it is larger than the sum of its proper divisors (587587).

21739313 is an equidigital number, since it uses as much as digits as its factorization.

21739313 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 587586.

The product of its digits is 3402, while the sum is 29.

The square root of 21739313 is about 4662.5436190989. The cubic root of 21739313 is about 279.0927822692.

The spelling of 21739313 in words is "twenty-one million, seven hundred thirty-nine thousand, three hundred thirteen".