19542115661 has 2 divisors, whose sum is σ = 19542115662. Its totient is φ = 19542115660.

The previous prime is 19542115627. The next prime is 19542115679. The reversal of 19542115661 is 16651124591.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 16691089636 + 2851026025 = 129194^2 + 53395^2 .

It is a cyclic number.

It is not a de Polignac number, because 19542115661 - 2⁶ = 19542115597 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (19542115601) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9771057830 + 9771057831.

It is an arithmetic number, because the mean of its divisors is an integer number (9771057831).

Almost surely, 2^19542115661 is an apocalyptic number.

It is an amenable number.

19542115661 is a deficient number, since it is larger than the sum of its proper divisors (1).

19542115661 is an equidigital number, since it uses as much as digits as its factorization.

19542115661 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 64800, while the sum is 41.

The spelling of 19542115661 in words is "nineteen billion, five hundred forty-two million, one hundred fifteen thousand, six hundred sixty-one".