19999333561 has 9 divisors (see below), whose sum is σ = 20210106639. Its totient is φ = 19790740536.

The previous prime is 19999333517. The next prime is 19999333567. The reversal of 19999333561 is 16533399991.

The square root of 19999333561 is 141419.

It is a perfect power (a square), and thus also a powerful number.

It can be written as a sum of positive squares in only one way, i.e., 19766954025 + 232379536 = 140595^2 + 15244^2 .

It is not a de Polignac number, because 19999333561 - 2⁹ = 19999333049 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 19999333496 and 19999333505.

It is not an unprimeable number, because it can be changed into a prime (19999333567) by changing a digit.

It is a polite number, since it can be written in 8 ways as a sum of consecutive naturals, for example, 14565471 + ... + 14566843.

Almost surely, 2^19999333561 is an apocalyptic number.

19999333561 is the 141419-th square number.

19999333561 is the 70710-th centered octagonal number.

It is an amenable number.

19999333561 is a deficient number, since it is larger than the sum of its proper divisors (210773078).

19999333561 is an frugal number, since it uses more digits than its factorization.

19999333561 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2952 (or 1476 counting only the distinct ones).

The product of its digits is 5314410, while the sum is 58.

The spelling of 19999333561 in words is "nineteen billion, nine hundred ninety-nine million, three hundred thirty-three thousand, five hundred sixty-one".