1644964656 has 160 divisors (see below), whose sum is σ = 4592467968. Its totient is φ = 506338560.

The previous prime is 1644964603. The next prime is 1644964681. The reversal of 1644964656 is 6564694461.

It is a junction number, because it is equal to n+sod(n) for n = 1644964599 and 1644964608.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 3006975 + ... + 3007521.

Almost surely, 2^1644964656 is an apocalyptic number.

1644964656 is a gapful number since it is divisible by the number (16) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 1644964656, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (2296233984).

1644964656 is an abundant number, since it is smaller than the sum of its proper divisors (2947503312).

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

1644964656 is a wasteful number, since it uses less digits than its factorization.

1644964656 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 679 (or 673 counting only the distinct ones).

The product of its digits is 3732480, while the sum is 51.

The square root of 1644964656 is about 40558.1638637648. The cubic root of 1644964656 is about 1180.4624865262.

The spelling of 1644964656 in words is "one billion, six hundred forty-four million, nine hundred sixty-four thousand, six hundred fifty-six".