21757013 has 2 divisors, whose sum is σ = 21757014. Its totient is φ = 21757012.

The previous prime is 21757007. The next prime is 21757037. The reversal of 21757013 is 31075712.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 21548164 + 208849 = 4642^2 + 457^2 .

It is a cyclic number.

It is not a de Polignac number, because 21757013 - 2⁴ = 21756997 is a prime.

It is a super-2 number, since 2×21757013² = 946735229364338, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21757213) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10878506 + 10878507.

It is an arithmetic number, because the mean of its divisors is an integer number (10878507).

Almost surely, 2^21757013 is an apocalyptic number.

It is an amenable number.

21757013 is a deficient number, since it is larger than the sum of its proper divisors (1).

21757013 is an equidigital number, since it uses as much as digits as its factorization.

21757013 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 1470, while the sum is 26.

The square root of 21757013 is about 4664.4413384670. The cubic root of 21757013 is about 279.1685068664.

The spelling of 21757013 in words is "twenty-one million, seven hundred fifty-seven thousand, thirteen".