721790221 has 8 divisors (see below), whose sum is σ = 766882080. Its totient is φ = 677408688.

The previous prime is 721790213. The next prime is 721790239. The reversal of 721790221 is 122097127.

It is a happy number.

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

It is a cyclic number.

It is not a de Polignac number, because 721790221 - 2³ = 721790213 is a prime.

It is a super-2 number, since 2×721790221² = 1041962246262457682, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (721796221) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 175486 + ... + 179551.

It is an arithmetic number, because the mean of its divisors is an integer number (95860260).

Almost surely, 2^721790221 is an apocalyptic number.

It is an amenable number.

721790221 is a deficient number, since it is larger than the sum of its proper divisors (45091859).

721790221 is a wasteful number, since it uses less digits than its factorization.

721790221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 355163.

The product of its (nonzero) digits is 3528, while the sum is 31.

The square root of 721790221 is about 26866.1538185130. The cubic root of 721790221 is about 897.0231775328.

The spelling of 721790221 in words is "seven hundred twenty-one million, seven hundred ninety thousand, two hundred twenty-one".