19806734021 has 2 divisors, whose sum is σ = 19806734022. Its totient is φ = 19806734020.

The previous prime is 19806734011. The next prime is 19806734071. The reversal of 19806734021 is 12043760891.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 19658844100 + 147889921 = 140210^2 + 12161^2 .

It is a cyclic number.

It is not a de Polignac number, because 19806734021 - 2²² = 19802539717 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 19806734021.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (19806734011) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9903367010 + 9903367011.

It is an arithmetic number, because the mean of its divisors is an integer number (9903367011).

Almost surely, 2^19806734021 is an apocalyptic number.

It is an amenable number.

19806734021 is a deficient number, since it is larger than the sum of its proper divisors (1).

19806734021 is an equidigital number, since it uses as much as digits as its factorization.

19806734021 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 72576, while the sum is 41.

The spelling of 19806734021 in words is "nineteen billion, eight hundred six million, seven hundred thirty-four thousand, twenty-one".