645689911 has 4 divisors (see below), whose sum is σ = 645837192. Its totient is φ = 645542632.

The previous prime is 645689887. The next prime is 645689983. The reversal of 645689911 is 119986546.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 645689911 - 2⁷ = 645689783 is a prime.

It is a super-2 number, since 2×645689911² = 833830922334375842, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (645689411) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 66856 + ... + 75901.

It is an arithmetic number, because the mean of its divisors is an integer number (161459298).

Almost surely, 2^645689911 is an apocalyptic number.

645689911 is a deficient number, since it is larger than the sum of its proper divisors (147281).

645689911 is a wasteful number, since it uses less digits than its factorization.

645689911 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 147280.

The product of its digits is 466560, while the sum is 49.

The square root of 645689911 is about 25410.4291778002. The cubic root of 645689911 is about 864.3202076554.

The spelling of 645689911 in words is "six hundred forty-five million, six hundred eighty-nine thousand, nine hundred eleven".