645918 has 48 divisors (see below), whose sum is σ = 1627920. Its totient is φ = 170352.

The previous prime is 645907. The next prime is 645937. The reversal of 645918 is 819546.

It is a congruent number.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 645918.

It is an unprimeable number.

645918 is an untouchable number, because it is not equal to the sum of proper divisors of any number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 49680 + ... + 49692.

It is an arithmetic number, because the mean of its divisors is an integer number (33915).

2⁶⁴⁵⁹¹⁸ is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 645918, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (813960).

645918 is an abundant number, since it is smaller than the sum of its proper divisors (982002).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

645918 is a wasteful number, since it uses less digits than its factorization.

645918 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 58 (or 25 counting only the distinct ones).

The product of its digits is 8640, while the sum is 33.

The square root of 645918 is about 803.6902388358. The cubic root of 645918 is about 86.4421968950.

The spelling of 645918 in words is "six hundred forty-five thousand, nine hundred eighteen".