21012001237 has 2 divisors, whose sum is σ = 21012001238. Its totient is φ = 21012001236.

The previous prime is 21012001217. The next prime is 21012001259. The reversal of 21012001237 is 73210021012.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 16633002961 + 4378998276 = 128969^2 + 66174^2 .

It is a cyclic number.

It is not a de Polignac number, because 21012001237 - 2²³ = 21003612629 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21012001217) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10506000618 + 10506000619.

It is an arithmetic number, because the mean of its divisors is an integer number (10506000619).

Almost surely, 2^21012001237 is an apocalyptic number.

It is an amenable number.

21012001237 is a deficient number, since it is larger than the sum of its proper divisors (1).

21012001237 is an equidigital number, since it uses as much as digits as its factorization.

21012001237 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 168, while the sum is 19.

Adding to 21012001237 its reverse (73210021012), we get a palindrome (94222022249).

The spelling of 21012001237 in words is "twenty-one billion, twelve million, one thousand, two hundred thirty-seven".