1644609051920 has 40 divisors (see below), whose sum is σ = 3880786447104. Its totient is φ = 648025057152.

The previous prime is 1644609051889. The next prime is 1644609051923. The reversal of 1644609051920 is 291509064461.

It is a tau number, because it is divible by the number of its divisors (40).

It is not an unprimeable number, because it can be changed into a prime (1644609051923) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 153409664 + ... + 153420383.

Almost surely, 2^{1644609051920} is an apocalyptic number.

1644609051920 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

1644609051920 is an abundant number, since it is smaller than the sum of its proper divisors (2236177395184).

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

1644609051920 is a wasteful number, since it uses less digits than its factorization.

1644609051920 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 306830127 (or 306830121 counting only the distinct ones).

The product of its (nonzero) digits is 466560, while the sum is 47.

The spelling of 1644609051920 in words is "one trillion, six hundred forty-four billion, six hundred nine million, fifty-one thousand, nine hundred twenty".