1643662644 has 48 divisors (see below), whose sum is σ = 4132802688. Its totient is φ = 505427328.

The previous prime is 1643662577. The next prime is 1643662661. The reversal of 1643662644 is 4462663461.

It is a nude number because it is divisible by every one of its digits.

It is a junction number, because it is equal to n+sod(n) for n = 1643662596 and 1643662605.

It is a congruent 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, 434449 + ... + 438215.

It is an arithmetic number, because the mean of its divisors is an integer number (86100056).

Almost surely, 2^1643662644 is an apocalyptic number.

It is an amenable number.

1643662644 is an abundant number, since it is smaller than the sum of its proper divisors (2489140044).

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

1643662644 is a wasteful number, since it uses less digits than its factorization.

1643662644 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6584 (or 6582 counting only the distinct ones).

The product of its digits is 497664, while the sum is 42.

The square root of 1643662644 is about 40542.1095159095. The cubic root of 1643662644 is about 1180.1509535887.

The spelling of 1643662644 in words is "one billion, six hundred forty-three million, six hundred sixty-two thousand, six hundred forty-four".