1985642564197 has 2 divisors, whose sum is σ = 1985642564198. Its totient is φ = 1985642564196.

The previous prime is 1985642564179. The next prime is 1985642564263. The reversal of 1985642564197 is 7914652465891.

Together with previous prime (1985642564179) it forms an Ormiston pair, because they use the same digits, order apart.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1880096199556 + 105546364641 = 1371166^2 + 324879^2 .

It is a cyclic number.

It is not a de Polignac number, because 1985642564197 - 2²⁷ = 1985508346469 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1985642564137) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 992821282098 + 992821282099.

It is an arithmetic number, because the mean of its divisors is an integer number (992821282099).

Almost surely, 2^{1985642564197} is an apocalyptic number.

It is an amenable number.

1985642564197 is a deficient number, since it is larger than the sum of its proper divisors (1).

1985642564197 is an equidigital number, since it uses as much as digits as its factorization.

1985642564197 is an evil number, because the sum of its binary digits is even.

The product of its digits is 130636800, while the sum is 67.

The spelling of 1985642564197 in words is "one trillion, nine hundred eighty-five billion, six hundred forty-two million, five hundred sixty-four thousand, one hundred ninety-seven".