645945 has 8 divisors (see below), whose sum is σ = 1033536. Its totient is φ = 344496.

The previous prime is 645941. The next prime is 645973. The reversal of 645945 is 549546.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 645945 - 2² = 645941 is a prime.

It is not an unprimeable number, because it can be changed into a prime (645941) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 21517 + ... + 21546.

It is an arithmetic number, because the mean of its divisors is an integer number (129192).

2⁶⁴⁵⁹⁴⁵ is an apocalyptic number.

It is an amenable number.

645945 is a deficient number, since it is larger than the sum of its proper divisors (387591).

645945 is a wasteful number, since it uses less digits than its factorization.

645945 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 43071.

The product of its digits is 21600, while the sum is 33.

The square root of 645945 is about 803.7070361767. The cubic root of 645945 is about 86.4434013341.

The spelling of 645945 in words is "six hundred forty-five thousand, nine hundred forty-five".