646445 has 4 divisors (see below), whose sum is σ = 775740. Its totient is φ = 517152.

The previous prime is 646433. The next prime is 646453. The reversal of 646445 is 544646.

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

It can be written as a sum of positive squares in 2 ways, for example, as 316969 + 329476 = 563^2 + 574^2 .

It is a cyclic number.

It is not a de Polignac number, because 646445 - 2⁸ = 646189 is a prime.

It is a super-2 number, since 2×646445² = 835782276050, which contains 22 as substring.

It is a d-powerful number, because it can be written as 6⁷ + 4⁴ + 4⁶ + 6⁷ + 4⁶ + 5⁷ .

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, 64640 + ... + 64649.

It is an arithmetic number, because the mean of its divisors is an integer number (193935).

2⁶⁴⁶⁴⁴⁵ is an apocalyptic number.

It is an amenable number.

646445 is a deficient number, since it is larger than the sum of its proper divisors (129295).

646445 is a wasteful number, since it uses less digits than its factorization.

646445 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 129294.

The product of its digits is 11520, while the sum is 29.

The square root of 646445 is about 804.0180346236. The cubic root of 646445 is about 86.4656996998.

Subtracting from 646445 its sum of digits (29), we obtain a square (646416 = 804²).

The spelling of 646445 in words is "six hundred forty-six thousand, four hundred forty-five".