645427 has 4 divisors (see below), whose sum is σ = 649696. Its totient is φ = 641160.

The previous prime is 645419. The next prime is 645431. The reversal of 645427 is 724546.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 645427 - 2³ = 645419 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 645395 and 645404.

It is not an unprimeable number, because it can be changed into a prime (645467) 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, 1899 + ... + 2212.

It is an arithmetic number, because the mean of its divisors is an integer number (162424).

2⁶⁴⁵⁴²⁷ is an apocalyptic number.

645427 is a deficient number, since it is larger than the sum of its proper divisors (4269).

645427 is a wasteful number, since it uses less digits than its factorization.

645427 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4268.

The product of its digits is 6720, while the sum is 28.

The square root of 645427 is about 803.3847148160. The cubic root of 645427 is about 86.4202880883.

The spelling of 645427 in words is "six hundred forty-five thousand, four hundred twenty-seven".