1999172891447 has 2 divisors, whose sum is σ = 1999172891448. Its totient is φ = 1999172891446.

The previous prime is 1999172891423. The next prime is 1999172891459. The reversal of 1999172891447 is 7441982719991.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 1999172891447 - 2⁶ = 1999172891383 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1999172891467) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 999586445723 + 999586445724.

It is an arithmetic number, because the mean of its divisors is an integer number (999586445724).

Almost surely, 2^{1999172891447} is an apocalyptic number.

1999172891447 is a deficient number, since it is larger than the sum of its proper divisors (1).

1999172891447 is an equidigital number, since it uses as much as digits as its factorization.

1999172891447 is an evil number, because the sum of its binary digits is even.

The product of its digits is 82301184, while the sum is 71.

The spelling of 1999172891447 in words is "one trillion, nine hundred ninety-nine billion, one hundred seventy-two million, eight hundred ninety-one thousand, four hundred forty-seven".