1644001920 has 576 divisors, whose sum is σ = 6636258720. Its totient is φ = 385689600.

The previous prime is 1644001913. The next prime is 1644001937. The reversal of 1644001920 is 291004461.

1644001920 is a `hidden beast` number, since 1 + 644 + 0 + 0 + 19 + 2 + 0 = 666.

1644001920 is digitally balanced in base 4, because in such base it contains all the possibile digits an equal number of times.

It is a tau number, because it is divible by the number of its divisors (576).

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 71 ways as a sum of consecutive naturals, for example, 53032305 + ... + 53032335.

Almost surely, 2^1644001920 is an apocalyptic number.

1644001920 is a gapful number since it is divisible by the number (10) 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 1644001920, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (3318129360).

1644001920 is an abundant number, since it is smaller than the sum of its proper divisors (4992256800).

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

1644001920 is an equidigital number, since it uses as much as digits as its factorization.

1644001920 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 107 (or 52 counting only the distinct ones).

The product of its (nonzero) digits is 1728, while the sum is 27.

The square root of 1644001920 is about 40546.2935420736. The cubic root of 1644001920 is about 1180.2321481392.

The spelling of 1644001920 in words is "one billion, six hundred forty-four million, one thousand, nine hundred twenty".