6721557066 has 60 divisors (see below), whose sum is σ = 17520269778. Its totient is φ = 1920442608.

The previous prime is 6721557061. The next prime is 6721557067. The reversal of 6721557066 is 6607551276.

6721557066 is a `hidden beast` number, since 6 + 7 + 2 + 15 + 570 + 66 = 666.

It can be written as a sum of positive squares in only one way, i.e., 4518662841 + 2202894225 = 67221^2 + 46935^2 .

It is not an unprimeable number, because it can be changed into a prime (6721557061) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 29 ways as a sum of consecutive naturals, for example, 415441 + ... + 431316.

Almost surely, 2^6721557066 is an apocalyptic number.

6721557066 is an abundant number, since it is smaller than the sum of its proper divisors (10798712712).

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

6721557066 is a wasteful number, since it uses less digits than its factorization.

6721557066 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 846785 (or 846769 counting only the distinct ones).

The product of its (nonzero) digits is 529200, while the sum is 45.

The square root of 6721557066 is about 81985.1027077481. The cubic root of 6721557066 is about 1887.2233300952.

The spelling of 6721557066 in words is "six billion, seven hundred twenty-one million, five hundred fifty-seven thousand, sixty-six".