5661221665 has 16 divisors (see below), whose sum is σ = 7801110720. Its totient is φ = 3900553920.

The previous prime is 5661221639. The next prime is 5661221681.

5661221665 is nontrivially palindromic in base 10.

It is not a de Polignac number, because 5661221665 - 2⁷ = 5661221537 is a prime.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 2707674 + ... + 2709763.

It is an arithmetic number, because the mean of its divisors is an integer number (487569420).

Almost surely, 2^5661221665 is an apocalyptic number.

5661221665 is a gapful number since it is divisible by the number (55) formed by its first and last digit.

It is an amenable number.

5661221665 is a deficient number, since it is larger than the sum of its proper divisors (2139889055).

5661221665 is a wasteful number, since it uses less digits than its factorization.

5661221665 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5417472.

The product of its digits is 129600, while the sum is 40.

The square root of 5661221665 is about 75241.0902698785. The cubic root of 5661221665 is about 1782.2558682166.

The spelling of 5661221665 in words is "five billion, six hundred sixty-one million, two hundred twenty-one thousand, six hundred sixty-five".