6650891809 has 3 divisors (see below), whose sum is σ = 6650973363. Its totient is φ = 6650810256.

The previous prime is 6650891801. The next prime is 6650891831. The reversal of 6650891809 is 9081980566.

The square root of 6650891809 is 81553.

It is a perfect power (a square), and thus also a powerful number.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It can be written as a sum of positive squares in only one way, i.e., 4410952225 + 2239939584 = 66415^2 + 47328^2 .

It is not a de Polignac number, because 6650891809 - 2³ = 6650891801 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (6650891801) by changing a digit.

It is a polite number, since it can be written in 2 ways as a sum of consecutive naturals, for example, 40777 + ... + 122329.

It is an arithmetic number, because the mean of its divisors is an integer number (2216991121).

Almost surely, 2^6650891809 is an apocalyptic number.

6650891809 is the 81553-rd square number.

6650891809 is the 40777-th centered octagonal number.

It is an amenable number.

6650891809 is a deficient number, since it is larger than the sum of its proper divisors (81554).

6650891809 is an frugal number, since it uses more digits than its factorization.

6650891809 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 163106 (or 81553 counting only the distinct ones).

The product of its (nonzero) digits is 933120, while the sum is 52.

The cubic root of 6650891809 is about 1880.5864144131.

The spelling of 6650891809 in words is "six billion, six hundred fifty million, eight hundred ninety-one thousand, eight hundred nine".