643876740 has 72 divisors (see below), whose sum is σ = 2103338328. Its totient is φ = 158492160.

The previous prime is 643876687. The next prime is 643876747. The reversal of 643876740 is 47678346.

It can be written as a sum of positive squares in 4 ways, for example, as 91814724 + 552062016 = 9582^2 + 23496^2 .

It is a Harshad number since it is a multiple of its sum of digits (45).

It is not an unprimeable number, because it can be changed into a prime (643876747) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 135241 + ... + 139920.

Almost surely, 2^643876740 is an apocalyptic number.

643876740 is a gapful number since it is divisible by the number (60) formed by its first and last digit.

It is an amenable number.

643876740 is an abundant number, since it is smaller than the sum of its proper divisors (1459461588).

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

643876740 is a wasteful number, since it uses less digits than its factorization.

643876740 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 275189 (or 275184 counting only the distinct ones).

The product of its (nonzero) digits is 677376, while the sum is 45.

The square root of 643876740 is about 25374.7264024659. The cubic root of 643876740 is about 863.5104125701.

The spelling of 643876740 in words is "six hundred forty-three million, eight hundred seventy-six thousand, seven hundred forty".