1321916509 has 4 divisors (see below), whose sum is σ = 1322108320. Its totient is φ = 1321724700.

The previous prime is 1321916503. The next prime is 1321916521. The reversal of 1321916509 is 9056191231.

It is a happy number.

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, and also an emirpimes, since its reverse is a distinct semiprime: 9056191231 = 31 ⋅292135201.

It is a cyclic number.

It is not a de Polignac number, because 1321916509 - 2²¹ = 1319819357 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 (1321916503) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 85167 + ... + 99484.

It is an arithmetic number, because the mean of its divisors is an integer number (330527080).

Almost surely, 2^1321916509 is an apocalyptic number.

It is an amenable number.

1321916509 is a deficient number, since it is larger than the sum of its proper divisors (191811).

1321916509 is an equidigital number, since it uses as much as digits as its factorization.

1321916509 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 191810.

The product of its (nonzero) digits is 14580, while the sum is 37.

The square root of 1321916509 is about 36358.1697696680. The cubic root of 1321916509 is about 1097.4919467448.

The spelling of 1321916509 in words is "one billion, three hundred twenty-one million, nine hundred sixteen thousand, five hundred nine".