640446161 has 4 divisors (see below), whose sum is σ = 641751024. Its totient is φ = 639141300.

The previous prime is 640446119. The next prime is 640446181. The reversal of 640446161 is 161644046.

640446161 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-640446161 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (640446101) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 651695 + ... + 652676.

It is an arithmetic number, because the mean of its divisors is an integer number (160437756).

Almost surely, 2^640446161 is an apocalyptic number.

It is an amenable number.

640446161 is a deficient number, since it is larger than the sum of its proper divisors (1304863).

640446161 is a wasteful number, since it uses less digits than its factorization.

640446161 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1304862.

The product of its (nonzero) digits is 13824, while the sum is 32.

The square root of 640446161 is about 25307.0377760812. The cubic root of 640446161 is about 861.9740846497.

The spelling of 640446161 in words is "six hundred forty million, four hundred forty-six thousand, one hundred sixty-one".