646769 has 4 divisors (see below), whose sum is σ = 648420. Its totient is φ = 645120.

The previous prime is 646757. The next prime is 646771. The reversal of 646769 is 967646.

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 409600 + 237169 = 640^2 + 487^2 .

It is a cyclic number.

It is not a de Polignac number, because 646769 - 2¹² = 642673 is a prime.

It is a super-2 number, since 2×646769² = 836620278722, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (646169) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 137 + ... + 1145.

It is an arithmetic number, because the mean of its divisors is an integer number (162105).

2⁶⁴⁶⁷⁶⁹ is an apocalyptic number.

It is an amenable number.

646769 is a deficient number, since it is larger than the sum of its proper divisors (1651).

646769 is a wasteful number, since it uses less digits than its factorization.

646769 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1650.

The product of its digits is 54432, while the sum is 38.

The square root of 646769 is about 804.2194974011. The cubic root of 646769 is about 86.4801429020.

The spelling of 646769 in words is "six hundred forty-six thousand, seven hundred sixty-nine".