1997306191 has 4 divisors (see below), whose sum is σ = 2015972712. Its totient is φ = 1978639672.

The previous prime is 1997306189. The next prime is 1997306231. The reversal of 1997306191 is 1916037991.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 1997306191 - 2¹ = 1997306189 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 (1997306491) 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, 9333100 + ... + 9333313.

It is an arithmetic number, because the mean of its divisors is an integer number (503993178).

Almost surely, 2^1997306191 is an apocalyptic number.

1997306191 is a deficient number, since it is larger than the sum of its proper divisors (18666521).

1997306191 is a wasteful number, since it uses less digits than its factorization.

1997306191 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 18666520.

The product of its (nonzero) digits is 91854, while the sum is 46.

The square root of 1997306191 is about 44691.2317015318. The cubic root of 1997306191 is about 1259.3551312954.

The spelling of 1997306191 in words is "one billion, nine hundred ninety-seven million, three hundred six thousand, one hundred ninety-one".