21726013 has 2 divisors, whose sum is σ = 21726014. Its totient is φ = 21726012.

The previous prime is 21725981. The next prime is 21726073. The reversal of 21726013 is 31062712.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 16426809 + 5299204 = 4053^2 + 2302^2 .

It is a cyclic number.

It is not a de Polignac number, because 21726013 - 2⁵ = 21725981 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21726073) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10863006 + 10863007.

It is an arithmetic number, because the mean of its divisors is an integer number (10863007).

Almost surely, 2^21726013 is an apocalyptic number.

It is an amenable number.

21726013 is a deficient number, since it is larger than the sum of its proper divisors (1).

21726013 is an equidigital number, since it uses as much as digits as its factorization.

21726013 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 504, while the sum is 22.

The square root of 21726013 is about 4661.1171407722. The cubic root of 21726013 is about 279.0358548149.

Adding to 21726013 its reverse (31062712), we get a palindrome (52788725).

The spelling of 21726013 in words is "twenty-one million, seven hundred twenty-six thousand, thirteen".