721166400 has 252 divisors, whose sum is σ = 2608388484. Its totient is φ = 188928000.

The previous prime is 721166399. The next prime is 721166419. The reversal of 721166400 is 4661127.

721166400 is a `hidden beast` number, since 7 + 2 + 1 + 16 + 640 + 0 = 666.

It can be written as a sum of positive squares in 6 ways, for example, as 204604416 + 516561984 = 14304^2 + 22728^2 .

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 35 ways as a sum of consecutive naturals, for example, 877990 + ... + 878810.

Almost surely, 2^721166400 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 721166400, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1304194242).

721166400 is an abundant number, since it is smaller than the sum of its proper divisors (1887222084).

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

721166400 is a wasteful number, since it uses less digits than its factorization.

721166400 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 910 (or 892 counting only the distinct ones).

The product of its (nonzero) digits is 2016, while the sum is 27.

The square root of 721166400 is about 26854.5415153564. The cubic root of 721166400 is about 896.7646799035.

The spelling of 721166400 in words is "seven hundred twenty-one million, one hundred sixty-six thousand, four hundred".