721384 has 8 divisors (see below), whose sum is σ = 1352610. Its totient is φ = 360688.

The previous prime is 721381. The next prime is 721387. The reversal of 721384 is 483127.

It is an interprime number because it is at equal distance from previous prime (721381) and next prime (721387).

It can be written as a sum of positive squares in only one way, i.e., 448900 + 272484 = 670^2 + 522^2 .

It is a tau number, because it is divible by the number of its divisors (8).

It is an Ulam number.

It is not an unprimeable number, because it can be changed into a prime (721381) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 45079 + ... + 45094.

2⁷²¹³⁸⁴ is an apocalyptic number.

It is an amenable number.

721384 is a deficient number, since it is larger than the sum of its proper divisors (631226).

721384 is a wasteful number, since it uses less digits than its factorization.

721384 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 90179 (or 90175 counting only the distinct ones).

The product of its digits is 1344, while the sum is 25.

The square root of 721384 is about 849.3432757137. The cubic root of 721384 is about 89.6854865456.

The spelling of 721384 in words is "seven hundred twenty-one thousand, three hundred eighty-four".