311661809 has 4 divisors (see below), whose sum is σ = 311716980. Its totient is φ = 311606640.

The previous prime is 311661793. The next prime is 311661839. The reversal of 311661809 is 908166113.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 908166113 = 41 ⋅22150393.

It can be written as a sum of positive squares in 2 ways, for example, as 4431025 + 307230784 = 2105^2 + 17528^2 .

It is a cyclic number.

It is not a de Polignac number, because 311661809 - 2⁴ = 311661793 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (311661839) 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, 18002 + ... + 30779.

It is an arithmetic number, because the mean of its divisors is an integer number (77929245).

Almost surely, 2^311661809 is an apocalyptic number.

It is an amenable number.

311661809 is a deficient number, since it is larger than the sum of its proper divisors (55171).

311661809 is an equidigital number, since it uses as much as digits as its factorization.

311661809 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 55170.

The product of its (nonzero) digits is 7776, while the sum is 35.

The square root of 311661809 is about 17653.9459894948. The cubic root of 311661809 is about 677.9971407774.

The spelling of 311661809 in words is "three hundred eleven million, six hundred sixty-one thousand, eight hundred nine".