1999999997 has 4 divisors (see below), whose sum is σ = 2037735900. Its totient is φ = 1962264096.

The previous prime is 1999999973. The next prime is 2000000011. The reversal of 1999999997 is 7999999991.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 7999999991 = 41 ⋅195121951.

It can be written as a sum of positive squares in 2 ways, for example, as 1497612601 + 502387396 = 38699^2 + 22414^2 .

It is a cyclic number.

It is not a de Polignac number, because 1999999997 - 2²⁰ = 1998951421 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1999999927) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 18867872 + ... + 18867977.

It is an arithmetic number, because the mean of its divisors is an integer number (509433975).

Almost surely, 2^1999999997 is an apocalyptic number.

It is an amenable number.

1999999997 is a deficient number, since it is larger than the sum of its proper divisors (37735903).

1999999997 is an equidigital number, since it uses as much as digits as its factorization.

1999999997 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 37735902.

The product of its digits is 301327047, while the sum is 80.

The square root of 1999999997 is about 44721.3595164548. The cubic root of 1999999997 is about 1259.9210492649.

The spelling of 1999999997 in words is "one billion, nine hundred ninety-nine million, nine hundred ninety-nine thousand, nine hundred ninety-seven".