1643344656 has 40 divisors (see below), whose sum is σ = 4468746720. Its totient is φ = 518950656.

The previous prime is 1643344643. The next prime is 1643344669. The reversal of 1643344656 is 6564433461.

It is an interprime number because it is at equal distance from previous prime (1643344643) and next prime (1643344669).

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 900045 + ... + 901868.

It is an arithmetic number, because the mean of its divisors is an integer number (111718668).

Almost surely, 2^1643344656 is an apocalyptic number.

1643344656 is a gapful number since it is divisible by the number (16) formed by its first and last digit.

It is an amenable number.

1643344656 is an abundant number, since it is smaller than the sum of its proper divisors (2825402064).

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

1643344656 is a wasteful number, since it uses less digits than its factorization.

1643344656 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1801943 (or 1801937 counting only the distinct ones).

The product of its digits is 622080, while the sum is 42.

The square root of 1643344656 is about 40538.1876259904. The cubic root of 1643344656 is about 1180.0748434765.

The spelling of 1643344656 in words is "one billion, six hundred forty-three million, three hundred forty-four thousand, six hundred fifty-six".