19964605391 has 2 divisors, whose sum is σ = 19964605392. Its totient is φ = 19964605390.

The previous prime is 19964605369. The next prime is 19964605483. The reversal of 19964605391 is 19350646991.

It is a happy number.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 19964605391 - 2²² = 19960411087 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (19964605301) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9982302695 + 9982302696.

It is an arithmetic number, because the mean of its divisors is an integer number (9982302696).

Almost surely, 2^19964605391 is an apocalyptic number.

19964605391 is a deficient number, since it is larger than the sum of its proper divisors (1).

19964605391 is an equidigital number, since it uses as much as digits as its factorization.

19964605391 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 1574640, while the sum is 53.

The spelling of 19964605391 in words is "nineteen billion, nine hundred sixty-four million, six hundred five thousand, three hundred ninety-one".