645887161 has 4 divisors (see below), whose sum is σ = 646081024. Its totient is φ = 645693300.

The previous prime is 645887153. The next prime is 645887189. The reversal of 645887161 is 161788546.

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, and also an emirpimes, since its reverse is a distinct semiprime: 161788546 = 2 ⋅80894273.

It is a cyclic number.

It is not a de Polignac number, because 645887161 - 2³ = 645887153 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (645887131) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 91845 + ... + 98626.

It is an arithmetic number, because the mean of its divisors is an integer number (161520256).

Almost surely, 2^645887161 is an apocalyptic number.

It is an amenable number.

645887161 is a deficient number, since it is larger than the sum of its proper divisors (193863).

645887161 is a wasteful number, since it uses less digits than its factorization.

645887161 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 193862.

The product of its digits is 322560, while the sum is 46.

The square root of 645887161 is about 25414.3101617966. The cubic root of 645887161 is about 864.4082116134.

The spelling of 645887161 in words is "six hundred forty-five million, eight hundred eighty-seven thousand, one hundred sixty-one".