1644231564 has 18 divisors (see below), whose sum is σ = 4156252100. Its totient is φ = 548077176.

The previous prime is 1644231559. The next prime is 1644231581. The reversal of 1644231564 is 4651324461.

1644231564 is a `hidden beast` number, since 1 + 64 + 4 + 2 + 31 + 564 = 666.

It is a tau number, because it is divible by the number of its divisors (18).

It is a super-3 number, since 3×1644231564³ (a number of 29 digits) contains 333 as substring.

It is a Harshad number since it is a multiple of its sum of digits (36), and also a Moran number because the ratio is a prime number: 45673099 = 1644231564 / (1 + 6 + 4 + 4 + 2 + 3 + 1 + 5 + 6 + 4).

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 22836514 + ... + 22836585.

Almost surely, 2^1644231564 is an apocalyptic number.

It is an amenable number.

1644231564 is an abundant number, since it is smaller than the sum of its proper divisors (2512020536).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

1644231564 is a wasteful number, since it uses less digits than its factorization.

1644231564 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 45673109 (or 45673104 counting only the distinct ones).

The product of its digits is 69120, while the sum is 36.

The square root of 1644231564 is about 40549.1253173234. The cubic root of 1644231564 is about 1180.2870995374.

The spelling of 1644231564 in words is "one billion, six hundred forty-four million, two hundred thirty-one thousand, five hundred sixty-four".