721980 has 96 divisors (see below), whose sum is σ = 2580480. Its totient is φ = 164160.

The previous prime is 721979. The next prime is 721991. The reversal of 721980 is 89127.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 3685 + ... + 3875.

It is an arithmetic number, because the mean of its divisors is an integer number (26880).

2⁷²¹⁹⁸⁰ is an apocalyptic number.

721980 is a gapful number since it is divisible by the number (70) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 721980, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1290240).

721980 is an abundant number, since it is smaller than the sum of its proper divisors (1858500).

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

721980 is a wasteful number, since it uses less digits than its factorization.

721980 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 216 (or 208 counting only the distinct ones).

The product of its (nonzero) digits is 1008, while the sum is 27.

The square root of 721980 is about 849.6940625896. The cubic root of 721980 is about 89.7101788205.

The spelling of 721980 in words is "seven hundred twenty-one thousand, nine hundred eighty".