721666000 has 80 divisors (see below), whose sum is σ = 1903681728. Its totient is φ = 262416000.

The previous prime is 721665983. The next prime is 721666013. The reversal of 721666000 is 666127.

It is a tau number, because it is divible by the number of its divisors (80).

It is a self number, because there is not a number n which added to its sum of digits gives 721666000.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 5599 + ... + 38401.

Almost surely, 2^721666000 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 721666000, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (951840864).

721666000 is an abundant number, since it is smaller than the sum of its proper divisors (1182015728).

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

721666000 is a wasteful number, since it uses less digits than its factorization.

721666000 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 32837 (or 32821 counting only the distinct ones).

The product of its (nonzero) digits is 3024, while the sum is 28.

The square root of 721666000 is about 26863.8418696954. The cubic root of 721666000 is about 896.9717149767.

The spelling of 721666000 in words is "seven hundred twenty-one million, six hundred sixty-six thousand".