19621491091 has 2 divisors, whose sum is σ = 19621491092. Its totient is φ = 19621491090.

The previous prime is 19621491037. The next prime is 19621491133. The reversal of 19621491091 is 19019412691.

It is a strong prime.

It is an emirp because it is prime and its reverse (19019412691) is a distict prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-19621491091 is a prime.

It is not a weakly prime, because it can be changed into another prime (19621491191) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9810745545 + 9810745546.

It is an arithmetic number, because the mean of its divisors is an integer number (9810745546).

Almost surely, 2^19621491091 is an apocalyptic number.

19621491091 is a deficient number, since it is larger than the sum of its proper divisors (1).

19621491091 is an equidigital number, since it uses as much as digits as its factorization.

19621491091 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 34992, while the sum is 43.

The spelling of 19621491091 in words is "nineteen billion, six hundred twenty-one million, four hundred ninety-one thousand, ninety-one".