721090 has 8 divisors (see below), whose sum is σ = 1297980. Its totient is φ = 288432.

The previous prime is 721087. The next prime is 721109. The reversal of 721090 is 90127.

721090 is nontrivially palindromic in base 9.

It can be written as a sum of positive squares in 2 ways, for example, as 720801 + 289 = 849^2 + 17^2 .

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

It is an alternating number because its digits alternate between odd and even.

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, 36045 + ... + 36064.

2⁷²¹⁰⁹⁰ is an apocalyptic number.

721090 is a deficient number, since it is larger than the sum of its proper divisors (576890).

721090 is a wasteful number, since it uses less digits than its factorization.

721090 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 72116.

The product of its (nonzero) digits is 126, while the sum is 19.

The square root of 721090 is about 849.1701831788. The cubic root of 721090 is about 89.6733011188.

The spelling of 721090 in words is "seven hundred twenty-one thousand, ninety".