19726643201 has 6 divisors (see below), whose sum is σ = 20819532402. Its totient is φ = 18688398480.

The previous prime is 19726643159. The next prime is 19726643221. The reversal of 19726643201 is 10234662791.

It can be written as a sum of positive squares in only one way, i.e., 18688257025 + 1038386176 = 136705^2 + 32224^2 .

It is a de Polignac number, because none of the positive numbers 2^k-19726643201 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (19726643221) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 27321860 + ... + 27322581.

It is an arithmetic number, because the mean of its divisors is an integer number (3469922067).

Almost surely, 2^19726643201 is an apocalyptic number.

It is an amenable number.

19726643201 is a deficient number, since it is larger than the sum of its proper divisors (1092889201).

19726643201 is an equidigital number, since it uses as much as digits as its factorization.

19726643201 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 54644479 (or 54644460 counting only the distinct ones).

The product of its (nonzero) digits is 108864, while the sum is 41.

The spelling of 19726643201 in words is "nineteen billion, seven hundred twenty-six million, six hundred forty-three thousand, two hundred one".