19685821913 has 2 divisors, whose sum is σ = 19685821914. Its totient is φ = 19685821912.

The previous prime is 19685821759. The next prime is 19685821999. The reversal of 19685821913 is 31912858691.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 13048949824 + 6636872089 = 114232^2 + 81467^2 .

It is a cyclic number.

It is not a de Polignac number, because 19685821913 - 2¹² = 19685817817 is a prime.

It is not a weakly prime, because it can be changed into another prime (19685821513) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9842910956 + 9842910957.

It is an arithmetic number, because the mean of its divisors is an integer number (9842910957).

Almost surely, 2^19685821913 is an apocalyptic number.

It is an amenable number.

19685821913 is a deficient number, since it is larger than the sum of its proper divisors (1).

19685821913 is an equidigital number, since it uses as much as digits as its factorization.

19685821913 is an evil number, because the sum of its binary digits is even.

The product of its digits is 933120, while the sum is 53.

The spelling of 19685821913 in words is "nineteen billion, six hundred eighty-five million, eight hundred twenty-one thousand, nine hundred thirteen".