6422165721 has 12 divisors (see below), whose sum is σ = 9277234980. Its totient is φ = 4281086880.

The previous prime is 6422165707. The next prime is 6422165779. The reversal of 6422165721 is 1275612246.

It is a happy number.

6422165721 is a `hidden beast` number, since 6 + 422 + 165 + 72 + 1 = 666.

It can be written as a sum of positive squares in 2 ways, for example, as 4272452496 + 2149713225 = 65364^2 + 46365^2 .

It is not a de Polignac number, because 6422165721 - 2¹⁵ = 6422132953 is a prime.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (6422165791) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 128535 + ... + 171363.

It is an arithmetic number, because the mean of its divisors is an integer number (773102915).

Almost surely, 2^6422165721 is an apocalyptic number.

It is an amenable number.

6422165721 is a deficient number, since it is larger than the sum of its proper divisors (2855069259).

6422165721 is a wasteful number, since it uses less digits than its factorization.

6422165721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 59496 (or 59493 counting only the distinct ones).

The product of its digits is 40320, while the sum is 36.

The square root of 6422165721 is about 80138.4160125467. The cubic root of 6422165721 is about 1858.7764837569.

Adding to 6422165721 its reverse (1275612246), we get a palindrome (7697777967).

The spelling of 6422165721 in words is "six billion, four hundred twenty-two million, one hundred sixty-five thousand, seven hundred twenty-one".