6566111061721 has 4 divisors (see below), whose sum is σ = 6689999949732. Its totient is φ = 6442222173712.

The previous prime is 6566111061709. The next prime is 6566111061733. The reversal of 6566111061721 is 1271601116656.

It is a semiprime because it is the product of two primes.

It is an interprime number because it is at equal distance from previous prime (6566111061709) and next prime (6566111061733).

It can be written as a sum of positive squares in 2 ways, for example, as 2620306237696 + 3945804824025 = 1618736^2 + 1986405^2 .

It is a cyclic number.

It is not a de Polignac number, because 6566111061721 - 2⁵ = 6566111061689 is a prime.

It is a super-2 number, since 2×6566111061721² (a number of 26 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (6566111061701) 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, 61944443926 + ... + 61944444031.

It is an arithmetic number, because the mean of its divisors is an integer number (1672499987433).

Almost surely, 2^{6566111061721} is an apocalyptic number.

It is an amenable number.

6566111061721 is a deficient number, since it is larger than the sum of its proper divisors (123888888011).

6566111061721 is a wasteful number, since it uses less digits than its factorization.

6566111061721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 123888888010.

The product of its (nonzero) digits is 90720, while the sum is 43.

The spelling of 6566111061721 in words is "six trillion, five hundred sixty-six billion, one hundred eleven million, sixty-one thousand, seven hundred twenty-one".