721222155561 has 8 divisors (see below), whose sum is σ = 1012241621920. Its totient is φ = 455508729792.

The previous prime is 721222155557. The next prime is 721222155571. The reversal of 721222155561 is 165551222127.

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

It is not a de Polignac number, because 721222155561 - 2² = 721222155557 is a prime.

It is a super-2 number, since 2×721222155561² (a number of 25 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (721222155551) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 6326510080 + ... + 6326510193.

It is an arithmetic number, because the mean of its divisors is an integer number (126530202740).

Almost surely, 2^721222155561 is an apocalyptic number.

It is an amenable number.

721222155561 is a deficient number, since it is larger than the sum of its proper divisors (291019466359).

721222155561 is a wasteful number, since it uses less digits than its factorization.

721222155561 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 12653020295.

The product of its digits is 84000, while the sum is 39.

Adding to 721222155561 its reverse (165551222127), we get a palindrome (886773377688).

The spelling of 721222155561 in words is "seven hundred twenty-one billion, two hundred twenty-two million, one hundred fifty-five thousand, five hundred sixty-one".