1999172112001 has 2 divisors, whose sum is σ = 1999172112002. Its totient is φ = 1999172112000.

The previous prime is 1999172111947. The next prime is 1999172112013. The reversal of 1999172112001 is 1002112719991.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 1048420357776 + 950751754225 = 1023924^2 + 975065^2 .

It is an emirp because it is prime and its reverse (1002112719991) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 1999172112001 - 2¹⁷ = 1999171980929 is a prime.

It is not a weakly prime, because it can be changed into another prime (1999172112071) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 999586056000 + 999586056001.

It is an arithmetic number, because the mean of its divisors is an integer number (999586056001).

Almost surely, 2^{1999172112001} is an apocalyptic number.

It is an amenable number.

1999172112001 is a deficient number, since it is larger than the sum of its proper divisors (1).

1999172112001 is an equidigital number, since it uses as much as digits as its factorization.

1999172112001 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 20412, while the sum is 43.

The spelling of 1999172112001 in words is "one trillion, nine hundred ninety-nine billion, one hundred seventy-two million, one hundred twelve thousand, one".