21810713 has 2 divisors, whose sum is σ = 21810714. Its totient is φ = 21810712.

The previous prime is 21810683. The next prime is 21810731. The reversal of 21810713 is 31701812.

It is a happy number.

Together with next prime (21810731) it forms an Ormiston pair, because they use the same digits, order apart.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 15272464 + 6538249 = 3908^2 + 2557^2 .

It is a cyclic number.

It is not a de Polignac number, because 21810713 - 2⁸ = 21810457 is a prime.

It is not a weakly prime, because it can be changed into another prime (21810793) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10905356 + 10905357.

It is an arithmetic number, because the mean of its divisors is an integer number (10905357).

Almost surely, 2^21810713 is an apocalyptic number.

It is an amenable number.

21810713 is a deficient number, since it is larger than the sum of its proper divisors (1).

21810713 is an equidigital number, since it uses as much as digits as its factorization.

21810713 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 336, while the sum is 23.

The square root of 21810713 is about 4670.1941073150. The cubic root of 21810713 is about 279.3979965789.

The spelling of 21810713 in words is "twenty-one million, eight hundred ten thousand, seven hundred thirteen".