1643443890 has 128 divisors (see below), whose sum is σ = 4619503872. Its totient is φ = 369745920.

The previous prime is 1643443861. The next prime is 1643443897. The reversal of 1643443890 is 983443461.

It is not an unprimeable number, because it can be changed into a prime (1643443897) by changing a digit.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 407524 + ... + 411536.

It is an arithmetic number, because the mean of its divisors is an integer number (36089874).

Almost surely, 2^1643443890 is an apocalyptic number.

1643443890 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is a practical number, because each smaller number is the sum of distinct divisors of 1643443890, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (2309751936).

1643443890 is an abundant number, since it is smaller than the sum of its proper divisors (2976059982).

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

1643443890 is a wasteful number, since it uses less digits than its factorization.

1643443890 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4124.

The product of its (nonzero) digits is 248832, while the sum is 42.

The square root of 1643443890 is about 40539.4115645504. The cubic root of 1643443890 is about 1180.0985960897.

The spelling of 1643443890 in words is "one billion, six hundred forty-three million, four hundred forty-three thousand, eight hundred ninety".