21756313 has 2 divisors, whose sum is σ = 21756314. Its totient is φ = 21756312.

The previous prime is 21756289. The next prime is 21756337. The reversal of 21756313 is 31365712.

It is a balanced prime because it is at equal distance from previous prime (21756289) and next prime (21756337).

It can be written as a sum of positive squares in only one way, i.e., 17867529 + 3888784 = 4227^2 + 1972^2 .

It is a cyclic number.

It is not a de Polignac number, because 21756313 - 2¹³ = 21748121 is a prime.

It is not a weakly prime, because it can be changed into another prime (21756353) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10878156 + 10878157.

It is an arithmetic number, because the mean of its divisors is an integer number (10878157).

Almost surely, 2^21756313 is an apocalyptic number.

It is an amenable number.

21756313 is a deficient number, since it is larger than the sum of its proper divisors (1).

21756313 is an equidigital number, since it uses as much as digits as its factorization.

21756313 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 3780, while the sum is 28.

The square root of 21756313 is about 4664.3663020822. The cubic root of 21756313 is about 279.1655128885.

The spelling of 21756313 in words is "twenty-one million, seven hundred fifty-six thousand, three hundred thirteen".