19901638879 has 2 divisors, whose sum is σ = 19901638880. Its totient is φ = 19901638878.

The previous prime is 19901638877. The next prime is 19901638903. The reversal of 19901638879 is 97883610991.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 19901638879 - 2¹ = 19901638877 is a prime.

Together with 19901638877, it forms a pair of twin primes.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (19901638877) 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, 9950819439 + 9950819440.

It is an arithmetic number, because the mean of its divisors is an integer number (9950819440).

Almost surely, 2^19901638879 is an apocalyptic number.

19901638879 is a deficient number, since it is larger than the sum of its proper divisors (1).

19901638879 is an equidigital number, since it uses as much as digits as its factorization.

19901638879 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 5878656, while the sum is 61.

The spelling of 19901638879 in words is "nineteen billion, nine hundred one million, six hundred thirty-eight thousand, eight hundred seventy-nine".