640066464 has 72 divisors (see below), whose sum is σ = 1824469920. Its totient is φ = 212853888.

The previous prime is 640066423. The next prime is 640066487. The reversal of 640066464 is 464660046.

It is a happy number.

640066464 is a `hidden beast` number, since 6 + 4 + 0 + 0 + 6 + 646 + 4 = 666.

It is a tau number, because it is divible by the number of its divisors (72).

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

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 132117 + ... + 136875.

It is an arithmetic number, because the mean of its divisors is an integer number (25339860).

Almost surely, 2^640066464 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 640066464, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (912234960).

640066464 is an abundant number, since it is smaller than the sum of its proper divisors (1184403456).

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

640066464 is a wasteful number, since it uses less digits than its factorization.

640066464 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5242 (or 5231 counting only the distinct ones).

The product of its (nonzero) digits is 82944, while the sum is 36.

The square root of 640066464 is about 25299.5348573842. The cubic root of 640066464 is about 861.8037067191.

The spelling of 640066464 in words is "six hundred forty million, sixty-six thousand, four hundred sixty-four".