640205261366 has 32 divisors (see below), whose sum is σ = 1060860302208. Its totient is φ = 287325533440.

The previous prime is 640205261341. The next prime is 640205261387. The reversal of 640205261366 is 663162502046.

It is a happy number.

It is a Curzon number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 2995421 + ... + 3202023.

It is an arithmetic number, because the mean of its divisors is an integer number (33151884444).

Almost surely, 2^640205261366 is an apocalyptic number.

640205261366 is a deficient number, since it is larger than the sum of its proper divisors (420655040842).

640205261366 is a wasteful number, since it uses less digits than its factorization.

640205261366 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 208396.

The product of its (nonzero) digits is 311040, while the sum is 41.

The spelling of 640205261366 in words is "six hundred forty billion, two hundred five million, two hundred sixty-one thousand, three hundred sixty-six".