19519928621 has 2 divisors, whose sum is σ = 19519928622. Its totient is φ = 19519928620.

The previous prime is 19519928587. The next prime is 19519928633. The reversal of 19519928621 is 12682991591.

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., 10264526596 + 9255402025 = 101314^2 + 96205^2 .

It is a cyclic number.

It is not a de Polignac number, because 19519928621 - 2³⁰ = 18446186797 is a prime.

It is a super-2 number, since 2×19519928621² (a number of 21 digits) contains 22 as substring.

It is a Sophie Germain prime.

It is a Curzon number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (19519922621) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9759964310 + 9759964311.

It is an arithmetic number, because the mean of its divisors is an integer number (9759964311).

Almost surely, 2^19519928621 is an apocalyptic number.

It is an amenable number.

19519928621 is a deficient number, since it is larger than the sum of its proper divisors (1).

19519928621 is an equidigital number, since it uses as much as digits as its factorization.

19519928621 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 699840, while the sum is 53.

The spelling of 19519928621 in words is "nineteen billion, five hundred nineteen million, nine hundred twenty-eight thousand, six hundred twenty-one".