640823616 has 112 divisors (see below), whose sum is σ = 1890979200. Its totient is φ = 212806656.

The previous prime is 640823611. The next prime is 640823663. The reversal of 640823616 is 616328046.

640823616 is a `hidden beast` number, since 6 + 408 + 236 + 16 = 666.

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

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (640823611) 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, 619836 + ... + 620868.

Almost surely, 2^640823616 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 640823616, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (945489600).

640823616 is an abundant number, since it is smaller than the sum of its proper divisors (1250155584).

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

640823616 is a wasteful number, since it uses less digits than its factorization.

640823616 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1413 (or 1397 counting only the distinct ones).

The product of its (nonzero) digits is 41472, while the sum is 36.

The square root of 640823616 is about 25314.4941881129. The cubic root of 640823616 is about 862.1433898160.

The spelling of 640823616 in words is "six hundred forty million, eight hundred twenty-three thousand, six hundred sixteen".