7721605557 has 64 divisors (see below), whose sum is σ = 11817388800. Its totient is φ = 4981616640.

The previous prime is 7721605543. The next prime is 7721605559. The reversal of 7721605557 is 7555061277.

It is a happy number.

7721605557 is a `hidden beast` number, since 77 + 21 + 6 + 0 + 5 + 557 = 666.

It is not a de Polignac number, because 7721605557 - 2¹⁴ = 7721589173 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (7721605559) 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 63 ways as a sum of consecutive naturals, for example, 36595182 + ... + 36595392.

It is an arithmetic number, because the mean of its divisors is an integer number (184646700).

Almost surely, 2^7721605557 is an apocalyptic number.

It is an amenable number.

7721605557 is a deficient number, since it is larger than the sum of its proper divisors (4095783243).

7721605557 is a wasteful number, since it uses less digits than its factorization.

7721605557 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 563 (or 557 counting only the distinct ones).

The product of its (nonzero) digits is 514500, while the sum is 45.

The square root of 7721605557 is about 87872.6667229350. Note that the first 3 decimals coincide. The cubic root of 7721605557 is about 1976.5260272860.

It can be divided in two parts, 7721 and 605557, that added together give a triangular number (613278 = T₁₁₀₇).

The spelling of 7721605557 in words is "seven billion, seven hundred twenty-one million, six hundred five thousand, five hundred fifty-seven".