721561280 has 112 divisors (see below), whose sum is σ = 1882932480. Its totient is φ = 261196800.

The previous prime is 721561261. The next prime is 721561297. The reversal of 721561280 is 82165127.

It is a Harshad number since it is a multiple of its sum of digits (32).

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, 1263395 + ... + 1263965.

Almost surely, 2^721561280 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 721561280, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (941466240).

721561280 is an abundant number, since it is smaller than the sum of its proper divisors (1161371200).

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

721561280 is a wasteful number, since it uses less digits than its factorization.

721561280 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 958 (or 948 counting only the distinct ones).

The product of its (nonzero) digits is 6720, while the sum is 32.

The square root of 721561280 is about 26861.8927106784. The cubic root of 721561280 is about 896.9283267511.

The spelling of 721561280 in words is "seven hundred twenty-one million, five hundred sixty-one thousand, two hundred eighty".