721202221 has 4 divisors (see below), whose sum is σ = 721349244. Its totient is φ = 721055200.

The previous prime is 721202201. The next prime is 721202233. The reversal of 721202221 is 122202127.

721202221 = 18989² + 18990².

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 360620100 + 360582121 = 18990^2 + 18989^2 .

It is a cyclic number.

It is not a de Polignac number, because 721202221 - 2⁷ = 721202093 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (721202201) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 65890 + ... + 76051.

It is an arithmetic number, because the mean of its divisors is an integer number (180337311).

Almost surely, 2^721202221 is an apocalyptic number.

721202221 is the 18990-th centered square number.

It is an amenable number.

721202221 is a deficient number, since it is larger than the sum of its proper divisors (147023).

721202221 is a wasteful number, since it uses less digits than its factorization.

721202221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 147022.

The product of its (nonzero) digits is 224, while the sum is 19.

The square root of 721202221 is about 26855.2084519931. The cubic root of 721202221 is about 896.7795273672.

Adding to 721202221 its reverse (122202127), we get a palindrome (843404348).

The spelling of 721202221 in words is "seven hundred twenty-one million, two hundred two thousand, two hundred twenty-one".