19391918551 has 2 divisors, whose sum is σ = 19391918552. Its totient is φ = 19391918550.

The previous prime is 19391918537. The next prime is 19391918561. The reversal of 19391918551 is 15581919391.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 19391918551 - 2⁵ = 19391918519 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (19391918501) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9695959275 + 9695959276.

It is an arithmetic number, because the mean of its divisors is an integer number (9695959276).

Almost surely, 2^19391918551 is an apocalyptic number.

19391918551 is a deficient number, since it is larger than the sum of its proper divisors (1).

19391918551 is an equidigital number, since it uses as much as digits as its factorization.

19391918551 is an evil number, because the sum of its binary digits is even.

The product of its digits is 437400, while the sum is 52.

The spelling of 19391918551 in words is "nineteen billion, three hundred ninety-one million, nine hundred eighteen thousand, five hundred fifty-one".