645361 has 4 divisors (see below), whose sum is σ = 648432. Its totient is φ = 642292.

The previous prime is 645353. The next prime is 645367. The reversal of 645361 is 163546.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 163546 = 2 ⋅81773.

It is a cyclic number.

It is not a de Polignac number, because 645361 - 2³ = 645353 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (645367) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1195 + ... + 1648.

It is an arithmetic number, because the mean of its divisors is an integer number (162108).

2⁶⁴⁵³⁶¹ is an apocalyptic number.

It is an amenable number.

645361 is a deficient number, since it is larger than the sum of its proper divisors (3071).

645361 is a wasteful number, since it uses less digits than its factorization.

645361 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3070.

The product of its digits is 2160, while the sum is 25.

The square root of 645361 is about 803.3436375549. The cubic root of 645361 is about 86.4173422693.

The spelling of 645361 in words is "six hundred forty-five thousand, three hundred sixty-one".