645963 has 8 divisors (see below), whose sum is σ = 866448. Its totient is φ = 428064.

The previous prime is 645941. The next prime is 645973. The reversal of 645963 is 369546.

It is a happy number.

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

It is not a de Polignac number, because 645963 - 2¹² = 641867 is a prime.

It is a Smith number, since the sum of its digits (33) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is not an unprimeable number, because it can be changed into a prime (645973) 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, 45 + ... + 1137.

It is an arithmetic number, because the mean of its divisors is an integer number (108306).

2⁶⁴⁵⁹⁶³ is an apocalyptic number.

645963 is a deficient number, since it is larger than the sum of its proper divisors (220485).

645963 is a wasteful number, since it uses less digits than its factorization.

645963 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1293.

The product of its digits is 19440, while the sum is 33.

The square root of 645963 is about 803.7182342090. The cubic root of 645963 is about 86.4442042749. Note that the first 3 decimals are identical.

The spelling of 645963 in words is "six hundred forty-five thousand, nine hundred sixty-three".