6621165540 has 144 divisors (see below), whose sum is σ = 22502450880. Its totient is φ = 1561731840.

The previous prime is 6621165539. The next prime is 6621165547. The reversal of 6621165540 is 455611266.

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

It is a junction number, because it is equal to n+sod(n) for n = 6621165495 and 6621165504.

It is not an unprimeable number, because it can be changed into a prime (6621165547) by changing a digit.

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 47 ways as a sum of consecutive naturals, for example, 28071 + ... + 118449.

It is an arithmetic number, because the mean of its divisors is an integer number (156267020).

Almost surely, 2^6621165540 is an apocalyptic number.

6621165540 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 6621165540, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (11251225440).

6621165540 is an abundant number, since it is smaller than the sum of its proper divisors (15881285340).

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

6621165540 is a wasteful number, since it uses less digits than its factorization.

6621165540 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 90442 (or 90437 counting only the distinct ones).

The product of its (nonzero) digits is 43200, while the sum is 36.

The square root of 6621165540 is about 81370.5446706608. The cubic root of 6621165540 is about 1877.7804593197.

The spelling of 6621165540 in words is "six billion, six hundred twenty-one million, one hundred sixty-five thousand, five hundred forty".