19661377531 has 2 divisors, whose sum is σ = 19661377532. Its totient is φ = 19661377530.

The previous prime is 19661377487. The next prime is 19661377607. The reversal of 19661377531 is 13577316691.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 19661377531 - 2⁹ = 19661377019 is a prime.

It is a super-2 number, since 2×19661377531² (a number of 21 digits) contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (19661317531) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9830688765 + 9830688766.

It is an arithmetic number, because the mean of its divisors is an integer number (9830688766).

Almost surely, 2^19661377531 is an apocalyptic number.

19661377531 is a deficient number, since it is larger than the sum of its proper divisors (1).

19661377531 is an equidigital number, since it uses as much as digits as its factorization.

19661377531 is an evil number, because the sum of its binary digits is even.

The product of its digits is 714420, while the sum is 49.

The spelling of 19661377531 in words is "nineteen billion, six hundred sixty-one million, three hundred seventy-seven thousand, five hundred thirty-one".