21637467403021 has 2 divisors, whose sum is σ = 21637467403022. Its totient is φ = 21637467403020.

The previous prime is 21637467403001. The next prime is 21637467403039. The reversal of 21637467403021 is 12030476473612.

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., 14094122757796 + 7543344645225 = 3754214^2 + 2746515^2 .

It is a cyclic number.

It is not a de Polignac number, because 21637467403021 - 2¹⁷ = 21637467271949 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21637467403001) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10818733701510 + 10818733701511.

It is an arithmetic number, because the mean of its divisors is an integer number (10818733701511).

Almost surely, 2^{21637467403021} is an apocalyptic number.

It is an amenable number.

21637467403021 is a deficient number, since it is larger than the sum of its proper divisors (1).

21637467403021 is an equidigital number, since it uses as much as digits as its factorization.

21637467403021 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 1016064, while the sum is 46.

The spelling of 21637467403021 in words is "twenty-one trillion, six hundred thirty-seven billion, four hundred sixty-seven million, four hundred three thousand, twenty-one".