21131713 has 2 divisors, whose sum is σ = 21131714. Its totient is φ = 21131712.

The previous prime is 21131711. The next prime is 21131723. The reversal of 21131713 is 31713112.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 13162384 + 7969329 = 3628^2 + 2823^2 .

It is a cyclic number.

It is not a de Polignac number, because 21131713 - 2¹ = 21131711 is a prime.

Together with 21131711, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (21131711) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10565856 + 10565857.

It is an arithmetic number, because the mean of its divisors is an integer number (10565857).

Almost surely, 2^21131713 is an apocalyptic number.

It is an amenable number.

21131713 is a deficient number, since it is larger than the sum of its proper divisors (1).

21131713 is an equidigital number, since it uses as much as digits as its factorization.

21131713 is an evil number, because the sum of its binary digits is even.

The product of its digits is 126, while the sum is 19.

The square root of 21131713 is about 4596.9242978322. The cubic root of 21131713 is about 276.4680193701.

Adding to 21131713 its reverse (31713112), we get a palindrome (52844825).

The spelling of 21131713 in words is "twenty-one million, one hundred thirty-one thousand, seven hundred thirteen".