1644138980 has 24 divisors (see below), whose sum is σ = 3766573440. Its totient is φ = 597868640.

The previous prime is 1644138961. The next prime is 1644138983. The reversal of 1644138980 is 898314461.

It is a super-3 number, since 3×1644138980³ (a number of 29 digits) contains 333 as substring.

It is a Harshad number since it is a multiple of its sum of digits (44).

It is not an unprimeable number, because it can be changed into a prime (1644138983) 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, 3736460 + ... + 3736899.

It is an arithmetic number, because the mean of its divisors is an integer number (156940560).

Almost surely, 2^1644138980 is an apocalyptic number.

1644138980 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

1644138980 is an abundant number, since it is smaller than the sum of its proper divisors (2122434460).

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

1644138980 is a wasteful number, since it uses less digits than its factorization.

1644138980 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7473379 (or 7473377 counting only the distinct ones).

The product of its (nonzero) digits is 165888, while the sum is 44.

The square root of 1644138980 is about 40547.9836736674. The cubic root of 1644138980 is about 1180.2649457739.

The spelling of 1644138980 in words is "one billion, six hundred forty-four million, one hundred thirty-eight thousand, nine hundred eighty".