1643396688 has 50 divisors (see below), whose sum is σ = 4756470554. Its totient is φ = 547798464.

The previous prime is 1643396683. The next prime is 1643396717. The reversal of 1643396688 is 8866933461.

It can be written as a sum of positive squares in only one way, i.e., 1150023744 + 493372944 = 33912^2 + 22212^2 .

It is a Harshad number since it is a multiple of its sum of digits (54).

It is a nude number because it is divisible by every one of its digits.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1643396683) by changing a digit.

It is a polite number, since it can be written in 9 ways as a sum of consecutive naturals, for example, 632731 + ... + 635322.

Almost surely, 2^1643396688 is an apocalyptic number.

1643396688 is a gapful number since it is divisible by the number (18) formed by its first and last digit.

It is an amenable number.

1643396688 is an abundant number, since it is smaller than the sum of its proper divisors (3113073866).

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

1643396688 is a wasteful number, since it uses less digits than its factorization.

1643396688 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1268073 (or 1268058 counting only the distinct ones).

The product of its digits is 4478976, while the sum is 54.

The square root of 1643396688 is about 40538.8293861577. The cubic root of 1643396688 is about 1180.0872979559.

The spelling of 1643396688 in words is "one billion, six hundred forty-three million, three hundred ninety-six thousand, six hundred eighty-eight".