21399492641 has 2 divisors, whose sum is σ = 21399492642. Its totient is φ = 21399492640.

The previous prime is 21399492607. The next prime is 21399492649. The reversal of 21399492641 is 14629499312.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 21280682641 + 118810000 = 145879^2 + 10900^2 .

It is a cyclic number.

It is not a de Polignac number, because 21399492641 - 2²⁶ = 21332383777 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21399492641.

It is not a weakly prime, because it can be changed into another prime (21399492649) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10699746320 + 10699746321.

It is an arithmetic number, because the mean of its divisors is an integer number (10699746321).

Almost surely, 2^21399492641 is an apocalyptic number.

It is an amenable number.

21399492641 is a deficient number, since it is larger than the sum of its proper divisors (1).

21399492641 is an equidigital number, since it uses as much as digits as its factorization.

21399492641 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 839808, while the sum is 50.

The spelling of 21399492641 in words is "twenty-one billion, three hundred ninety-nine million, four hundred ninety-two thousand, six hundred forty-one".