6406440660 has 240 divisors, whose sum is σ = 20678454720. Its totient is φ = 1659709440.

The previous prime is 6406440647. The next prime is 6406440697. The reversal of 6406440660 is 660446046.

It is a happy number.

6406440660 is a `hidden beast` number, since 6 + 4 + 0 + 644 + 0 + 6 + 6 + 0 = 666.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 79 ways as a sum of consecutive naturals, for example, 9270915 + ... + 9271605.

It is an arithmetic number, because the mean of its divisors is an integer number (86160228).

Almost surely, 2^6406440660 is an apocalyptic number.

6406440660 is a gapful number since it is divisible by the number (60) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 6406440660, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (10339227360).

6406440660 is an abundant number, since it is smaller than the sum of its proper divisors (14272014060).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

6406440660 is a wasteful number, since it uses less digits than its factorization.

6406440660 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 868 (or 857 counting only the distinct ones).

The product of its (nonzero) digits is 82944, while the sum is 36.

The square root of 6406440660 is about 80040.2440026266. The cubic root of 6406440660 is about 1857.2581349632.

The spelling of 6406440660 in words is "six billion, four hundred six million, four hundred forty thousand, six hundred sixty".