6409661 has 4 divisors (see below), whose sum is σ = 6530652. Its totient is φ = 6288672.

The previous prime is 6409651. The next prime is 6409673. The reversal of 6409661 is 1669046.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 1669046 = 2 ⋅834523.

It can be written as a sum of positive squares in 2 ways, for example, as 5317636 + 1092025 = 2306^2 + 1045^2 .

It is a cyclic number.

It is not a de Polignac number, because 6409661 - 2¹⁰ = 6408637 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (6409651) 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, 60416 + ... + 60521.

It is an arithmetic number, because the mean of its divisors is an integer number (1632663).

Almost surely, 2^6409661 is an apocalyptic number.

It is an amenable number.

6409661 is a deficient number, since it is larger than the sum of its proper divisors (120991).

6409661 is a wasteful number, since it uses less digits than its factorization.

6409661 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 120990.

The product of its (nonzero) digits is 7776, while the sum is 32.

The square root of 6409661 is about 2531.7308308744. The cubic root of 6409661 is about 185.7569280215.

It can be divided in two parts, 640 and 9661, that added together give a palindrome (10301).

The spelling of 6409661 in words is "six million, four hundred nine thousand, six hundred sixty-one".