21990013 has 2 divisors, whose sum is σ = 21990014. Its totient is φ = 21990012.

The previous prime is 21989999. The next prime is 21990041. The reversal of 21990013 is 31009912.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 11985444 + 10004569 = 3462^2 + 3163^2 .

It is a cyclic number.

It is not a de Polignac number, because 21990013 - 2⁹ = 21989501 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21990013.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21990043) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10995006 + 10995007.

It is an arithmetic number, because the mean of its divisors is an integer number (10995007).

Almost surely, 2^21990013 is an apocalyptic number.

It is an amenable number.

21990013 is a deficient number, since it is larger than the sum of its proper divisors (1).

21990013 is an equidigital number, since it uses as much as digits as its factorization.

21990013 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 486, while the sum is 25.

The square root of 21990013 is about 4689.3510211969. The cubic root of 21990013 is about 280.1615266983.

Adding to 21990013 its reverse (31009912), we get a palindrome (52999925).

The spelling of 21990013 in words is "twenty-one million, nine hundred ninety thousand, thirteen".