1664644265 has 16 divisors (see below), whose sum is σ = 2032321536. Its totient is φ = 1308720000.

The previous prime is 1664644259. The next prime is 1664644307. The reversal of 1664644265 is 5624464661.

It is not a de Polignac number, because 1664644265 - 2⁴ = 1664644249 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 68765 + ... + 89765.

It is an arithmetic number, because the mean of its divisors is an integer number (127020096).

Almost surely, 2^1664644265 is an apocalyptic number.

It is an amenable number.

1664644265 is a deficient number, since it is larger than the sum of its proper divisors (367677271).

1664644265 is a wasteful number, since it uses less digits than its factorization.

1664644265 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 21280.

The product of its digits is 829440, while the sum is 44.

The square root of 1664644265 is about 40800.0522671234. The cubic root of 1664644265 is about 1185.1513429283.

The spelling of 1664644265 in words is "one billion, six hundred sixty-four million, six hundred forty-four thousand, two hundred sixty-five".