1643972740 has 24 divisors (see below), whose sum is σ = 3468713472. Its totient is φ = 654470880.

The previous prime is 1643972723. The next prime is 1643972747. The reversal of 1643972740 is 472793461.

It is not an unprimeable number, because it can be changed into a prime (1643972747) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 190564 + ... + 199003.

It is an arithmetic number, because the mean of its divisors is an integer number (144529728).

Almost surely, 2^1643972740 is an apocalyptic number.

1643972740 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

1643972740 is an abundant number, since it is smaller than the sum of its proper divisors (1824740732).

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

1643972740 is a wasteful number, since it uses less digits than its factorization.

1643972740 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 389787 (or 389785 counting only the distinct ones).

The product of its (nonzero) digits is 254016, while the sum is 43.

The square root of 1643972740 is about 40545.9337048735. The cubic root of 1643972740 is about 1180.2251653051.

The spelling of 1643972740 in words is "one billion, six hundred forty-three million, nine hundred seventy-two thousand, seven hundred forty".