721363518866 has 4 divisors (see below), whose sum is σ = 1082045278302. Its totient is φ = 360681759432.

The previous prime is 721363518859. The next prime is 721363518961. The reversal of 721363518866 is 668815363127.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 668815363127 = 134087 ⋅4987921.

It can be written as a sum of positive squares in only one way, i.e., 500515215841 + 220848303025 = 707471^2 + 469945^2 .

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 180340879715 + ... + 180340879718.

Almost surely, 2^721363518866 is an apocalyptic number.

721363518866 is a deficient number, since it is larger than the sum of its proper divisors (360681759436).

721363518866 is a wasteful number, since it uses less digits than its factorization.

721363518866 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 360681759435.

The product of its digits is 8709120, while the sum is 56.

The spelling of 721363518866 in words is "seven hundred twenty-one billion, three hundred sixty-three million, five hundred eighteen thousand, eight hundred sixty-six".