21530713 has 2 divisors, whose sum is σ = 21530714. Its totient is φ = 21530712.

The previous prime is 21530711. The next prime is 21530741. The reversal of 21530713 is 31703512.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 19465744 + 2064969 = 4412^2 + 1437^2 .

It is a cyclic number.

It is not a de Polignac number, because 21530713 - 2¹ = 21530711 is a prime.

Together with 21530711, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (21530711) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10765356 + 10765357.

It is an arithmetic number, because the mean of its divisors is an integer number (10765357).

Almost surely, 2^21530713 is an apocalyptic number.

It is an amenable number.

21530713 is a deficient number, since it is larger than the sum of its proper divisors (1).

21530713 is an equidigital number, since it uses as much as digits as its factorization.

21530713 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 630, while the sum is 22.

The square root of 21530713 is about 4640.1199337948. The cubic root of 21530713 is about 278.1972316368.

The spelling of 21530713 in words is "twenty-one million, five hundred thirty thousand, seven hundred thirteen".