643137840 has 160 divisors (see below), whose sum is σ = 2331993600. Its totient is φ = 162466560.

The previous prime is 643137793. The next prime is 643137851. The reversal of 643137840 is 48731346.

643137840 is a `hidden beast` number, since 643 + 1 + 3 + 7 + 8 + 4 + 0 = 666.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a junction number, because it is equal to n+sod(n) for n = 643137795 and 643137804.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 33205 + ... + 48875.

It is an arithmetic number, because the mean of its divisors is an integer number (14574960).

Almost surely, 2^643137840 is an apocalyptic number.

643137840 is a gapful number since it is divisible by the number (60) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 643137840, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1165996800).

643137840 is an abundant number, since it is smaller than the sum of its proper divisors (1688855760).

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

643137840 is a wasteful number, since it uses less digits than its factorization.

643137840 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 15712 (or 15700 counting only the distinct ones).

The product of its (nonzero) digits is 48384, while the sum is 36.

The square root of 643137840 is about 25360.1624600475. The cubic root of 643137840 is about 863.1799704061.

The spelling of 643137840 in words is "six hundred forty-three million, one hundred thirty-seven thousand, eight hundred forty".