206640864 has 72 divisors (see below), whose sum is σ = 596461320. Its totient is φ = 67845888.

The previous prime is 206640851. The next prime is 206640869. The reversal of 206640864 is 468046602.

It is a happy number.

206640864 is a `hidden beast` number, since 2 + 0 + 6 + 640 + 8 + 6 + 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 a congruent number.

It is not an unprimeable number, because it can be changed into a prime (206640869) by changing a digit.

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 11 ways as a sum of consecutive naturals, for example, 13942 + ... + 24650.

It is an arithmetic number, because the mean of its divisors is an integer number (8284185).

Almost surely, 2^206640864 is an apocalyptic number.

206640864 is a gapful number since it is divisible by the number (24) 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 206640864, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (298230660).

206640864 is an abundant number, since it is smaller than the sum of its proper divisors (389820456).

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

206640864 is a wasteful number, since it uses less digits than its factorization.

206640864 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10792 (or 10781 counting only the distinct ones).

The product of its (nonzero) digits is 55296, while the sum is 36.

The square root of 206640864 is about 14375.0083130411. The cubic root of 206640864 is about 591.2058684825.

The spelling of 206640864 in words is "two hundred six million, six hundred forty thousand, eight hundred sixty-four".