21266331389 has 2 divisors, whose sum is σ = 21266331390. Its totient is φ = 21266331388.

The previous prime is 21266331353. The next prime is 21266331431. The reversal of 21266331389 is 98313366212.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 15888602500 + 5377728889 = 126050^2 + 73333^2 .

It is a cyclic number.

It is not a de Polignac number, because 21266331389 - 2⁸ = 21266331133 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21266331329) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10633165694 + 10633165695.

It is an arithmetic number, because the mean of its divisors is an integer number (10633165695).

Almost surely, 2^21266331389 is an apocalyptic number.

It is an amenable number.

21266331389 is a deficient number, since it is larger than the sum of its proper divisors (1).

21266331389 is an equidigital number, since it uses as much as digits as its factorization.

21266331389 is an evil number, because the sum of its binary digits is even.

The product of its digits is 279936, while the sum is 44.

The spelling of 21266331389 in words is "twenty-one billion, two hundred sixty-six million, three hundred thirty-one thousand, three hundred eighty-nine".