646436240 has 80 divisors (see below), whose sum is σ = 1597814400. Its totient is φ = 242528256.

The previous prime is 646436179. The next prime is 646436249. The reversal of 646436240 is 42634646.

It is a tau number, because it is divible by the number of its divisors (80).

It is a self number, because there is not a number n which added to its sum of digits gives 646436240.

It is not an unprimeable number, because it can be changed into a prime (646436249) 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, 154496 + ... + 158624.

It is an arithmetic number, because the mean of its divisors is an integer number (19972680).

Almost surely, 2^646436240 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 646436240, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (798907200).

646436240 is an abundant number, since it is smaller than the sum of its proper divisors (951378160).

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

646436240 is a wasteful number, since it uses less digits than its factorization.

646436240 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4264 (or 4258 counting only the distinct ones).

The product of its (nonzero) digits is 82944, while the sum is 35.

The square root of 646436240 is about 25425.1104225724. The cubic root of 646436240 is about 864.6530913138.

The spelling of 646436240 in words is "six hundred forty-six million, four hundred thirty-six thousand, two hundred forty".