640255896 has 192 divisors, whose sum is σ = 2095441920. Its totient is φ = 172730880.

The previous prime is 640255801. The next prime is 640255897. The reversal of 640255896 is 698552046.

640255896 is a `hidden beast` number, since 6 + 4 + 0 + 2 + 558 + 96 = 666.

It is a super-2 number, since 2×640255896² = 819855224725525632, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (640255897) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 671356 + ... + 672308.

It is an arithmetic number, because the mean of its divisors is an integer number (10913760).

Almost surely, 2^640255896 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 640255896, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1047720960).

640255896 is an abundant number, since it is smaller than the sum of its proper divisors (1455186024).

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

640255896 is a wasteful number, since it uses less digits than its factorization.

640255896 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1046 (or 1039 counting only the distinct ones).

The product of its (nonzero) digits is 518400, while the sum is 45.

The square root of 640255896 is about 25303.2783646705. The cubic root of 640255896 is about 861.8887172122. Note that the first 3 decimals are identical.

The spelling of 640255896 in words is "six hundred forty million, two hundred fifty-five thousand, eight hundred ninety-six".