645245 has 4 divisors (see below), whose sum is σ = 774300. Its totient is φ = 516192.

The previous prime is 645233. The next prime is 645257. The reversal of 645245 is 542546.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 542546 = 2 ⋅271273.

It is an interprime number because it is at equal distance from previous prime (645233) and next prime (645257).

It can be written as a sum of positive squares in 2 ways, for example, as 454276 + 190969 = 674^2 + 437^2 .

It is a cyclic number.

It is not a de Polignac number, because 645245 - 2¹⁴ = 628861 is a prime.

It is a super-2 number, since 2×645245² = 832682220050, which contains 22 as substring.

It is a Curzon number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 64520 + ... + 64529.

It is an arithmetic number, because the mean of its divisors is an integer number (193575).

2⁶⁴⁵²⁴⁵ is an apocalyptic number.

It is an amenable number.

645245 is a deficient number, since it is larger than the sum of its proper divisors (129055).

645245 is a wasteful number, since it uses less digits than its factorization.

645245 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 129054.

The product of its digits is 4800, while the sum is 26.

The square root of 645245 is about 803.2714360663. The cubic root of 645245 is about 86.4121642824.

The spelling of 645245 in words is "six hundred forty-five thousand, two hundred forty-five".