721968 has 60 divisors (see below), whose sum is σ = 2042280. Its totient is φ = 219648.

The previous prime is 721961. The next prime is 721979. The reversal of 721968 is 869127.

It is an Ulam number.

Its product of digits (6048) is a multiple of the sum of its prime factors (126).

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 721968.

It is not an unprimeable number, because it can be changed into a prime (721961) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 8068 + ... + 8156.

It is an arithmetic number, because the mean of its divisors is an integer number (34038).

2⁷²¹⁹⁶⁸ is an apocalyptic number.

721968 is a gapful number since it is divisible by the number (78) 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 721968, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1021140).

721968 is an abundant number, since it is smaller than the sum of its proper divisors (1320312).

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

721968 is a wasteful number, since it uses less digits than its factorization.

721968 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 126 (or 107 counting only the distinct ones).

The product of its digits is 6048, while the sum is 33.

The square root of 721968 is about 849.6870011951. The cubic root of 721968 is about 89.7096817947.

The spelling of 721968 in words is "seven hundred twenty-one thousand, nine hundred sixty-eight".