721940 has 12 divisors (see below), whose sum is σ = 1516116. Its totient is φ = 288768.

The previous prime is 721921. The next prime is 721951. The reversal of 721940 is 49127.

It can be written as a sum of positive squares in 2 ways, for example, as 183184 + 538756 = 428^2 + 734^2 .

It is a congruent number.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 721940.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 18029 + ... + 18068.

It is an arithmetic number, because the mean of its divisors is an integer number (126343).

2⁷²¹⁹⁴⁰ is an apocalyptic number.

It is an amenable number.

721940 is an abundant number, since it is smaller than the sum of its proper divisors (794176).

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

721940 is a wasteful number, since it uses less digits than its factorization.

721940 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 36106 (or 36104 counting only the distinct ones).

The product of its (nonzero) digits is 504, while the sum is 23.

The square root of 721940 is about 849.6705243799. The cubic root of 721940 is about 89.7085220464.

It can be divided in two parts, 721 and 940, that added together give a palindrome (1661).

The spelling of 721940 in words is "seven hundred twenty-one thousand, nine hundred forty".