21339517 has 4 divisors (see below), whose sum is σ = 21350620. Its totient is φ = 21328416.

The previous prime is 21339511. The next prime is 21339529. The reversal of 21339517 is 71593312.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It can be written as a sum of positive squares in 2 ways, for example, as 16168441 + 5171076 = 4021^2 + 2274^2 .

It is a cyclic number.

It is not a de Polignac number, because 21339517 - 2³ = 21339509 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 (21339511) 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, 1842 + ... + 6787.

It is an arithmetic number, because the mean of its divisors is an integer number (5337655).

Almost surely, 2^21339517 is an apocalyptic number.

It is an amenable number.

21339517 is a deficient number, since it is larger than the sum of its proper divisors (11103).

21339517 is an equidigital number, since it uses as much as digits as its factorization.

21339517 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 11102.

The product of its digits is 5670, while the sum is 31.

The square root of 21339517 is about 4619.4715065687. The cubic root of 21339517 is about 277.3713041203.

The spelling of 21339517 in words is "twenty-one million, three hundred thirty-nine thousand, five hundred seventeen".