21021199937 has 2 divisors, whose sum is σ = 21021199938. Its totient is φ = 21021199936.

The previous prime is 21021199921. The next prime is 21021199973. The reversal of 21021199937 is 73999112012.

Together with next prime (21021199973) it forms an Ormiston pair, because they use the same digits, order apart.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 13988029441 + 7033170496 = 118271^2 + 83864^2 .

It is a cyclic number.

It is not a de Polignac number, because 21021199937 - 2⁴ = 21021199921 is a prime.

It is not a weakly prime, because it can be changed into another prime (21021198937) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10510599968 + 10510599969.

It is an arithmetic number, because the mean of its divisors is an integer number (10510599969).

Almost surely, 2^21021199937 is an apocalyptic number.

It is an amenable number.

21021199937 is a deficient number, since it is larger than the sum of its proper divisors (1).

21021199937 is an equidigital number, since it uses as much as digits as its factorization.

21021199937 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 61236, while the sum is 44.

The spelling of 21021199937 in words is "twenty-one billion, twenty-one million, one hundred ninety-nine thousand, nine hundred thirty-seven".