1643813956 has 48 divisors (see below), whose sum is σ = 3167861760. Its totient is φ = 742880160.

The previous prime is 1643813953. The next prime is 1643814017. The reversal of 1643813956 is 6593183461.

It is a Harshad number since it is a multiple of its sum of digits (46).

It is not an unprimeable number, because it can be changed into a prime (1643813953) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 850311 + ... + 852241.

It is an arithmetic number, because the mean of its divisors is an integer number (65997120).

Almost surely, 2^1643813956 is an apocalyptic number.

It is an amenable number.

1643813956 is a deficient number, since it is larger than the sum of its proper divisors (1524047804).

1643813956 is a wasteful number, since it uses less digits than its factorization.

1643813956 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2464 (or 2462 counting only the distinct ones).

The product of its digits is 466560, while the sum is 46.

The square root of 1643813956 is about 40543.9755820763. The cubic root of 1643813956 is about 1180.1871665189.

The spelling of 1643813956 in words is "one billion, six hundred forty-three million, eight hundred thirteen thousand, nine hundred fifty-six".