645880169 has 4 divisors (see below), whose sum is σ = 704596560. Its totient is φ = 587163780.

The previous prime is 645880163. The next prime is 645880189. The reversal of 645880169 is 961088546.

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 not a de Polignac number, because 645880169 - 2²⁴ = 629102953 is a prime.

It is a super-2 number, since 2×645880169² = 834322385414937122, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (645880163) 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, 29358179 + ... + 29358200.

It is an arithmetic number, because the mean of its divisors is an integer number (176149140).

Almost surely, 2^645880169 is an apocalyptic number.

It is an amenable number.

645880169 is a deficient number, since it is larger than the sum of its proper divisors (58716391).

645880169 is a wasteful number, since it uses less digits than its factorization.

645880169 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 58716390.

The product of its (nonzero) digits is 414720, while the sum is 47.

The square root of 645880169 is about 25414.1726011295. The cubic root of 645880169 is about 864.4050924080.

The spelling of 645880169 in words is "six hundred forty-five million, eight hundred eighty thousand, one hundred sixty-nine".