21999013 has 2 divisors, whose sum is σ = 21999014. Its totient is φ = 21999012.

The previous prime is 21999007. The next prime is 21999041. The reversal of 21999013 is 31099912.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 21687649 + 311364 = 4657^2 + 558^2 .

It is a cyclic number.

It is not a de Polignac number, because 21999013 - 2¹³ = 21990821 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21999013.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21999073) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10999506 + 10999507.

It is an arithmetic number, because the mean of its divisors is an integer number (10999507).

Almost surely, 2^21999013 is an apocalyptic number.

It is an amenable number.

21999013 is a deficient number, since it is larger than the sum of its proper divisors (1).

21999013 is an equidigital number, since it uses as much as digits as its factorization.

21999013 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 4374, while the sum is 34.

The square root of 21999013 is about 4690.3105440898. The cubic root of 21999013 is about 280.1997426804.

The spelling of 21999013 in words is "twenty-one million, nine hundred ninety-nine thousand, thirteen".