721666650 has 24 divisors (see below), whose sum is σ = 1789733664. Its totient is φ = 192444400.

The previous prime is 721666633. The next prime is 721666663. The reversal of 721666650 is 56666127.

It is a Curzon number.

It is a junction number, because it is equal to n+sod(n) for n = 721666599 and 721666608.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 2405406 + ... + 2405705.

It is an arithmetic number, because the mean of its divisors is an integer number (74572236).

Almost surely, 2^721666650 is an apocalyptic number.

721666650 is an abundant number, since it is smaller than the sum of its proper divisors (1068067014).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

721666650 is a wasteful number, since it uses less digits than its factorization.

721666650 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4811126 (or 4811121 counting only the distinct ones).

The product of its (nonzero) digits is 90720, while the sum is 39.

The square root of 721666650 is about 26863.8539677389. The cubic root of 721666650 is about 896.9719842756.

The spelling of 721666650 in words is "seven hundred twenty-one million, six hundred sixty-six thousand, six hundred fifty".