1997760809 has 4 divisors (see below), whose sum is σ = 2179375440. Its totient is φ = 1816146180.

The previous prime is 1997760799. The next prime is 1997760811. The reversal of 1997760809 is 9080677991.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1997760809 is a prime.

It is not an unprimeable number, because it can be changed into a prime (1997760209) 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, 90807299 + ... + 90807320.

It is an arithmetic number, because the mean of its divisors is an integer number (544843860).

Almost surely, 2^1997760809 is an apocalyptic number.

It is an amenable number.

1997760809 is a deficient number, since it is larger than the sum of its proper divisors (181614631).

1997760809 is a wasteful number, since it uses less digits than its factorization.

1997760809 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 181614630.

The product of its (nonzero) digits is 1714608, while the sum is 56.

The square root of 1997760809 is about 44696.3176223724. The cubic root of 1997760809 is about 1259.4506736615.

The spelling of 1997760809 in words is "one billion, nine hundred ninety-seven million, seven hundred sixty thousand, eight hundred nine".