19690172644321 has 3 divisors (see below), whose sum is σ = 19690177081683. Its totient is φ = 19690168206960.

The previous prime is 19690172644319. The next prime is 19690172644327. The reversal of 19690172644321 is 12344627109691.

The square root of 19690172644321 is 4437361.

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

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It can be written as a sum of positive squares in only one way, i.e., 11583397026721 + 8106775617600 = 3403439^2 + 2847240^2 .

It is not a de Polignac number, because 19690172644321 - 2¹ = 19690172644319 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (19690172644327) by changing a digit.

It is a polite number, since it can be written in 2 ways as a sum of consecutive naturals, for example, 2218681 + ... + 6656041.

It is an arithmetic number, because the mean of its divisors is an integer number (6563392360561).

Almost surely, 2^{19690172644321} is an apocalyptic number.

19690172644321 is the 4437361-st square number.

19690172644321 is the 2218681-st centered octagonal number.

It is an amenable number.

19690172644321 is a deficient number, since it is larger than the sum of its proper divisors (4437362).

19690172644321 is an frugal number, since it uses more digits than its factorization.

19690172644321 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8874722 (or 4437361 counting only the distinct ones).

The product of its (nonzero) digits is 3919104, while the sum is 55.

The spelling of 19690172644321 in words is "nineteen trillion, six hundred ninety billion, one hundred seventy-two million, six hundred forty-four thousand, three hundred twenty-one".