21012331009 has 2 divisors, whose sum is σ = 21012331010. Its totient is φ = 21012331008.

The previous prime is 21012331003. The next prime is 21012331033. The reversal of 21012331009 is 90013321012.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 20888342784 + 123988225 = 144528^2 + 11135^2 .

It is a cyclic number.

It is not a de Polignac number, because 21012331009 - 2²¹ = 21010233857 is a prime.

It is not a weakly prime, because it can be changed into another prime (21012331003) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10506165504 + 10506165505.

It is an arithmetic number, because the mean of its divisors is an integer number (10506165505).

Almost surely, 2^21012331009 is an apocalyptic number.

It is an amenable number.

21012331009 is a deficient number, since it is larger than the sum of its proper divisors (1).

21012331009 is an equidigital number, since it uses as much as digits as its factorization.

21012331009 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 324, while the sum is 22.

The spelling of 21012331009 in words is "twenty-one billion, twelve million, three hundred thirty-one thousand, nine".