21012099989 has 2 divisors, whose sum is σ = 21012099990. Its totient is φ = 21012099988.

The previous prime is 21012099937. The next prime is 21012100033. The reversal of 21012099989 is 98999021012.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 20458439089 + 553660900 = 143033^2 + 23530^2 .

It is a cyclic number.

It is not a de Polignac number, because 21012099989 - 2²⁴ = 20995322773 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21012099929) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10506049994 + 10506049995.

It is an arithmetic number, because the mean of its divisors is an integer number (10506049995).

Almost surely, 2^21012099989 is an apocalyptic number.

It is an amenable number.

21012099989 is a deficient number, since it is larger than the sum of its proper divisors (1).

21012099989 is an equidigital number, since it uses as much as digits as its factorization.

21012099989 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 209952, while the sum is 50.

The spelling of 21012099989 in words is "twenty-one billion, twelve million, ninety-nine thousand, nine hundred eighty-nine".