721390 has 8 divisors (see below), whose sum is σ = 1298520. Its totient is φ = 288552.

The previous prime is 721387. The next prime is 721397. The reversal of 721390 is 93127.

721390 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (721397) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 36060 + ... + 36079.

It is an arithmetic number, because the mean of its divisors is an integer number (162315).

2⁷²¹³⁹⁰ is an apocalyptic number.

721390 is a deficient number, since it is larger than the sum of its proper divisors (577130).

721390 is a wasteful number, since it uses less digits than its factorization.

721390 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 72146.

The product of its (nonzero) digits is 378, while the sum is 22.

The square root of 721390 is about 849.3468078471. The cubic root of 721390 is about 89.6857351933.

It can be divided in two parts, 721 and 390, that added together give a palindrome (1111).

The spelling of 721390 in words is "seven hundred twenty-one thousand, three hundred ninety".