21123713 has 8 divisors (see below), whose sum is σ = 22785000. Its totient is φ = 19467648.

The previous prime is 21123709. The next prime is 21123721. The reversal of 21123713 is 31732112.

It can be written as a sum of positive squares in 4 ways, for example, as 2521744 + 18601969 = 1588^2 + 4313^2 .

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 21123713 - 2² = 21123709 is a prime.

It is a super-2 number, since 2×21123713² = 892422501812738, which contains 22 as substring.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (21123013) 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, 12863 + ... + 14411.

It is an arithmetic number, because the mean of its divisors is an integer number (2848125).

Almost surely, 2^21123713 is an apocalyptic number.

It is an amenable number.

21123713 is a deficient number, since it is larger than the sum of its proper divisors (1661287).

21123713 is a wasteful number, since it uses less digits than its factorization.

21123713 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2611.

The product of its digits is 252, while the sum is 20.

The square root of 21123713 is about 4596.0540684374. The cubic root of 21123713 is about 276.4331267370.

Adding to 21123713 its reverse (31732112), we get a palindrome (52855825).

The spelling of 21123713 in words is "twenty-one million, one hundred twenty-three thousand, seven hundred thirteen".