1217897809 has 8 divisors (see below), whose sum is σ = 1251343040. Its totient is φ = 1184480496.

The previous prime is 1217897783. The next prime is 1217897843. The reversal of 1217897809 is 9087987121.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 1217897809 - 2⁹ = 1217897297 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1217897309) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 106252 + ... + 117154.

It is an arithmetic number, because the mean of its divisors is an integer number (156417880).

Almost surely, 2^1217897809 is an apocalyptic number.

It is an amenable number.

1217897809 is a deficient number, since it is larger than the sum of its proper divisors (33445231).

1217897809 is a wasteful number, since it uses less digits than its factorization.

1217897809 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 13959.

The product of its (nonzero) digits is 508032, while the sum is 52.

The square root of 1217897809 is about 34898.3926420688. The cubic root of 1217897809 is about 1067.9156468163.

The spelling of 1217897809 in words is "one billion, two hundred seventeen million, eight hundred ninety-seven thousand, eight hundred nine".