19661377487 has 2 divisors, whose sum is σ = 19661377488. Its totient is φ = 19661377486.

The previous prime is 19661377469. The next prime is 19661377531. The reversal of 19661377487 is 78477316691.

It is a happy number.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 19661377487 - 2¹⁰ = 19661376463 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (19661377987) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9830688743 + 9830688744.

It is an arithmetic number, because the mean of its divisors is an integer number (9830688744).

Almost surely, 2^19661377487 is an apocalyptic number.

19661377487 is a deficient number, since it is larger than the sum of its proper divisors (1).

19661377487 is an equidigital number, since it uses as much as digits as its factorization.

19661377487 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 10668672, while the sum is 59.

The spelling of 19661377487 in words is "nineteen billion, six hundred sixty-one million, three hundred seventy-seven thousand, four hundred eighty-seven".