660520809 has 24 divisors (see below), whose sum is σ = 1029380352. Its totient is φ = 405721440.

The previous prime is 660520801. The next prime is 660520829. The reversal of 660520809 is 908025066.

It is not a de Polignac number, because 660520809 - 2³ = 660520801 is a prime.

It is not an unprimeable number, because it can be changed into a prime (660520801) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 61864 + ... + 71750.

It is an arithmetic number, because the mean of its divisors is an integer number (42890848).

Almost surely, 2^660520809 is an apocalyptic number.

It is an amenable number.

660520809 is a deficient number, since it is larger than the sum of its proper divisors (368859543).

660520809 is a wasteful number, since it uses less digits than its factorization.

660520809 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10477 (or 10474 counting only the distinct ones).

The product of its (nonzero) digits is 25920, while the sum is 36.

The square root of 660520809 is about 25700.5993898975. The cubic root of 660520809 is about 870.8877225026.

The spelling of 660520809 in words is "six hundred sixty million, five hundred twenty thousand, eight hundred nine".