21937513 has 8 divisors (see below), whose sum is σ = 23731400. Its totient is φ = 20158848.

The previous prime is 21937499. The next prime is 21937519. The reversal of 21937513 is 31573912.

It can be written as a sum of positive squares in 4 ways, for example, as 9320809 + 12616704 = 3053^2 + 3552^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 21937513 - 2¹³ = 21929321 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21937519) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 708 + ... + 6661.

It is an arithmetic number, because the mean of its divisors is an integer number (2966425).

Almost surely, 2^21937513 is an apocalyptic number.

It is an amenable number.

21937513 is a deficient number, since it is larger than the sum of its proper divisors (1793887).

21937513 is a wasteful number, since it uses less digits than its factorization.

21937513 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7611.

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

The square root of 21937513 is about 4683.7498865759. The cubic root of 21937513 is about 279.9383920577.

The spelling of 21937513 in words is "twenty-one million, nine hundred thirty-seven thousand, five hundred thirteen".