721111122221 has 32 divisors (see below), whose sum is σ = 878871840000. Its totient is φ = 577931231232.

The previous prime is 721111122203. The next prime is 721111122239. The reversal of 721111122221 is 122221111127.

It is an interprime number because it is at equal distance from previous prime (721111122203) and next prime (721111122239).

It is a cyclic number.

It is not a de Polignac number, because 721111122221 - 2¹⁰ = 721111121197 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (721111122521) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 3628955 + ... + 3822503.

It is an arithmetic number, because the mean of its divisors is an integer number (27464745000).

Almost surely, 2^721111122221 is an apocalyptic number.

It is an amenable number.

721111122221 is a deficient number, since it is larger than the sum of its proper divisors (157760717779).

721111122221 is a wasteful number, since it uses less digits than its factorization.

721111122221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 193941.

The product of its digits is 224, while the sum is 23.

Adding to 721111122221 its reverse (122221111127), we get a palindrome (843332233348).

The spelling of 721111122221 in words is "seven hundred twenty-one billion, one hundred eleven million, one hundred twenty-two thousand, two hundred twenty-one".