391121407609 has 3 divisors (see below), whose sum is σ = 391122033007. Its totient is φ = 391120782212.

The previous prime is 391121407531. The next prime is 391121407613. The reversal of 391121407609 is 906704121193.

The square root of 391121407609 is 625397.

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., 9409970025 + 381711437584 = 97005^2 + 617828^2 .

It is not a de Polignac number, because 391121407609 - 2⁹ = 391121407097 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (391121407669) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 2 ways as a sum of consecutive naturals, for example, 312699 + ... + 938095.

Almost surely, 2^391121407609 is an apocalyptic number.

391121407609 is the 625397-th square number.

391121407609 is the 312699-th centered octagonal number.

It is an amenable number.

391121407609 is a deficient number, since it is larger than the sum of its proper divisors (625398).

391121407609 is an frugal number, since it uses more digits than its factorization.

391121407609 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1250794 (or 625397 counting only the distinct ones).

The product of its (nonzero) digits is 81648, while the sum is 43.

The spelling of 391121407609 in words is "three hundred ninety-one billion, one hundred twenty-one million, four hundred seven thousand, six hundred nine".