721661166127 has 32 divisors (see below), whose sum is σ = 857608349184. Its totient is φ = 599915289600.

The previous prime is 721661166077. The next prime is 721661166139.

721661166127 is nontrivially palindromic in base 10.

It is not a de Polignac number, because 721661166127 - 2⁷ = 721661165999 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (721661166197) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 520102 + ... + 1309132.

It is an arithmetic number, because the mean of its divisors is an integer number (26800260912).

Almost surely, 2^721661166127 is an apocalyptic number.

721661166127 is a deficient number, since it is larger than the sum of its proper divisors (135947183057).

721661166127 is a wasteful number, since it uses less digits than its factorization.

721661166127 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 789199.

The product of its digits is 254016, while the sum is 46.

It can be divided in two parts, 721661 and 166127, that added together give a palindrome (887788).

The spelling of 721661166127 in words is "seven hundred twenty-one billion, six hundred sixty-one million, one hundred sixty-six thousand, one hundred twenty-seven".