721727617663 has 4 divisors (see below), whose sum is σ = 777245126728. Its totient is φ = 666210108600.

The previous prime is 721727617649. The next prime is 721727617679. The reversal of 721727617663 is 366716727127.

721727617663 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 366716727127 = 261787 ⋅1400821.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-721727617663 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (721727617763) 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, 27758754513 + ... + 27758754538.

It is an arithmetic number, because the mean of its divisors is an integer number (194311281682).

Almost surely, 2^721727617663 is an apocalyptic number.

721727617663 is a deficient number, since it is larger than the sum of its proper divisors (55517509065).

721727617663 is a wasteful number, since it uses less digits than its factorization.

721727617663 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 55517509064.

The product of its digits is 6223392, while the sum is 55.

The spelling of 721727617663 in words is "seven hundred twenty-one billion, seven hundred twenty-seven million, six hundred seventeen thousand, six hundred sixty-three".