6440661 has 16 divisors (see below), whose sum is σ = 9630720. Its totient is φ = 4253760.

The previous prime is 6440647. The next prime is 6440683. The reversal of 6440661 is 1660446.

It is not a de Polignac number, because 6440661 - 2⁹ = 6440149 is a prime.

It is a super-2 number, since 2×6440661² = 82964228233842, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (6440641) 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 15 ways as a sum of consecutive naturals, for example, 1996 + ... + 4106.

It is an arithmetic number, because the mean of its divisors is an integer number (601920).

Almost surely, 2^6440661 is an apocalyptic number.

It is an amenable number.

6440661 is a deficient number, since it is larger than the sum of its proper divisors (3190059).

6440661 is a wasteful number, since it uses less digits than its factorization.

6440661 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2233 (or 2227 counting only the distinct ones).

The product of its (nonzero) digits is 3456, while the sum is 27.

The square root of 6440661 is about 2537.8457399929. The cubic root of 6440661 is about 186.0559145111.

The spelling of 6440661 in words is "six million, four hundred forty thousand, six hundred sixty-one".