19721995345 has 32 divisors (see below), whose sum is σ = 27753465600. Its totient is φ = 13321615104.

The previous prime is 19721995309. The next prime is 19721995417. The reversal of 19721995345 is 54359912791.

It is a cyclic number.

It is not a de Polignac number, because 19721995345 - 2⁹ = 19721994833 is a prime.

It is a Smith number, since the sum of its digits (55) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 239517 + ... + 311146.

It is an arithmetic number, because the mean of its divisors is an integer number (867295800).

Almost surely, 2^19721995345 is an apocalyptic number.

It is an amenable number.

19721995345 is a deficient number, since it is larger than the sum of its proper divisors (8031470255).

19721995345 is a wasteful number, since it uses less digits than its factorization.

19721995345 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 550729.

The product of its digits is 3061800, while the sum is 55.

It can be divided in two parts, 19721995 and 345, that added together give a triangular number (19722340 = T₆₂₈₀).

The spelling of 19721995345 in words is "nineteen billion, seven hundred twenty-one million, nine hundred ninety-five thousand, three hundred forty-five".