721388 has 6 divisors (see below), whose sum is σ = 1262436. Its totient is φ = 360692.

The previous prime is 721387. The next prime is 721397. The reversal of 721388 is 883127.

It is a self number, because there is not a number n which added to its sum of digits gives 721388.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 721388.

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, 90170 + ... + 90177.

It is an arithmetic number, because the mean of its divisors is an integer number (210406).

2⁷²¹³⁸⁸ is an apocalyptic number.

It is an amenable number.

721388 is a deficient number, since it is larger than the sum of its proper divisors (541048).

721388 is a wasteful number, since it uses less digits than its factorization.

721388 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 180351 (or 180349 counting only the distinct ones).

The product of its digits is 2688, while the sum is 29.

The square root of 721388 is about 849.3456304709. The cubic root of 721388 is about 89.6856523109.

The spelling of 721388 in words is "seven hundred twenty-one thousand, three hundred eighty-eight".