19987400491 has 2 divisors, whose sum is σ = 19987400492. Its totient is φ = 19987400490.

The previous prime is 19987400413. The next prime is 19987400557. The reversal of 19987400491 is 19400478991.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 19987400491 - 2¹⁵ = 19987367723 is a prime.

It is not a weakly prime, because it can be changed into another prime (19987401491) 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, 9993700245 + 9993700246.

It is an arithmetic number, because the mean of its divisors is an integer number (9993700246).

Almost surely, 2^19987400491 is an apocalyptic number.

19987400491 is a deficient number, since it is larger than the sum of its proper divisors (1).

19987400491 is an equidigital number, since it uses as much as digits as its factorization.

19987400491 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 653184, while the sum is 52.

The spelling of 19987400491 in words is "nineteen billion, nine hundred eighty-seven million, four hundred thousand, four hundred ninety-one".