21156713 has 2 divisors, whose sum is σ = 21156714. Its totient is φ = 21156712.

The previous prime is 21156703. The next prime is 21156719. The reversal of 21156713 is 31765112.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 20403289 + 753424 = 4517^2 + 868^2 .

It is a cyclic number.

It is not a de Polignac number, because 21156713 - 2¹⁸ = 20894569 is a prime.

It is not a weakly prime, because it can be changed into another prime (21156719) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10578356 + 10578357.

It is an arithmetic number, because the mean of its divisors is an integer number (10578357).

Almost surely, 2^21156713 is an apocalyptic number.

It is an amenable number.

21156713 is a deficient number, since it is larger than the sum of its proper divisors (1).

21156713 is an equidigital number, since it uses as much as digits as its factorization.

21156713 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1260, while the sum is 26.

The square root of 21156713 is about 4599.6427035151. The cubic root of 21156713 is about 276.5770021208.

The spelling of 21156713 in words is "twenty-one million, one hundred fifty-six thousand, seven hundred thirteen".