19928991091 has 4 divisors (see below), whose sum is σ = 19976328784. Its totient is φ = 19881653400.

The previous prime is 19928991067. The next prime is 19928991101. The reversal of 19928991091 is 19019982991.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 19019982991 = 691 ⋅27525301.

It is a cyclic number.

It is not a de Polignac number, because 19928991091 - 2¹¹ = 19928989043 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (19928991041) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 23668215 + ... + 23669056.

It is an arithmetic number, because the mean of its divisors is an integer number (4994082196).

Almost surely, 2^19928991091 is an apocalyptic number.

19928991091 is a deficient number, since it is larger than the sum of its proper divisors (47337693).

19928991091 is an equidigital number, since it uses as much as digits as its factorization.

19928991091 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 47337692.

The product of its (nonzero) digits is 944784, while the sum is 58.

The spelling of 19928991091 in words is "nineteen billion, nine hundred twenty-eight million, nine hundred ninety-one thousand, ninety-one".