21901613 has 2 divisors, whose sum is σ = 21901614. Its totient is φ = 21901612.

The previous prime is 21901603. The next prime is 21901619. The reversal of 21901613 is 31610912.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 17330569 + 4571044 = 4163^2 + 2138^2 .

It is a cyclic number.

It is not a de Polignac number, because 21901613 - 2¹⁴ = 21885229 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21901619) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10950806 + 10950807.

It is an arithmetic number, because the mean of its divisors is an integer number (10950807).

Almost surely, 2^21901613 is an apocalyptic number.

It is an amenable number.

21901613 is a deficient number, since it is larger than the sum of its proper divisors (1).

21901613 is an equidigital number, since it uses as much as digits as its factorization.

21901613 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 324, while the sum is 23.

The square root of 21901613 is about 4679.9159180481. The cubic root of 21901613 is about 279.7856054389.

The spelling of 21901613 in words is "twenty-one million, nine hundred one thousand, six hundred thirteen".