21173013 has 6 divisors (see below), whose sum is σ = 30583254. Its totient is φ = 14115336.

The previous prime is 21172999. The next prime is 21173021. The reversal of 21173013 is 31037112.

It can be written as a sum of positive squares in only one way, i.e., 19342404 + 1830609 = 4398^2 + 1353^2 .

It is not a de Polignac number, because 21173013 - 2⁴ = 21172997 is a prime.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21173413) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 1176270 + ... + 1176287.

It is an arithmetic number, because the mean of its divisors is an integer number (5097209).

Almost surely, 2^21173013 is an apocalyptic number.

It is an amenable number.

21173013 is a deficient number, since it is larger than the sum of its proper divisors (9410241).

21173013 is a wasteful number, since it uses less digits than its factorization.

21173013 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2352563 (or 2352560 counting only the distinct ones).

The product of its (nonzero) digits is 126, while the sum is 18.

The square root of 21173013 is about 4601.4142391226. The cubic root of 21173013 is about 276.6480126453.

The spelling of 21173013 in words is "twenty-one million, one hundred seventy-three thousand, thirteen".