645290 has 16 divisors (see below), whose sum is σ = 1171368. Its totient is φ = 255936.

The previous prime is 645257. The next prime is 645313. The reversal of 645290 is 92546.

645290 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It can be written as a sum of positive squares in 4 ways, for example, as 619369 + 25921 = 787^2 + 161^2 .

It is a Curzon number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1544 + ... + 1916.

2⁶⁴⁵²⁹⁰ is an apocalyptic number.

645290 is a deficient number, since it is larger than the sum of its proper divisors (526078).

645290 is a wasteful number, since it uses less digits than its factorization.

645290 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 553.

The product of its (nonzero) digits is 2160, while the sum is 26.

The square root of 645290 is about 803.2994460349. The cubic root of 645290 is about 86.4141730579.

The spelling of 645290 in words is "six hundred forty-five thousand, two hundred ninety".