645909187 has 16 divisors (see below), whose sum is σ = 805900032. Its totient is φ = 502924320.

The previous prime is 645909181. The next prime is 645909193. The reversal of 645909187 is 781909546.

It is an interprime number because it is at equal distance from previous prime (645909181) and next prime (645909193).

It is a cyclic number.

It is not a de Polignac number, because 645909187 - 2⁷ = 645909059 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 645909187.

It is not an unprimeable number, because it can be changed into a prime (645909181) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 141513 + ... + 146005.

It is an arithmetic number, because the mean of its divisors is an integer number (50368752).

Almost surely, 2^645909187 is an apocalyptic number.

645909187 is a deficient number, since it is larger than the sum of its proper divisors (159990845).

645909187 is a wasteful number, since it uses less digits than its factorization.

645909187 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6378.

The product of its (nonzero) digits is 544320, while the sum is 49.

The square root of 645909187 is about 25414.7434966399. The cubic root of 645909187 is about 864.4180374983.

The spelling of 645909187 in words is "six hundred forty-five million, nine hundred nine thousand, one hundred eighty-seven".