1721221111 has 8 divisors (see below), whose sum is σ = 1751872320. Its totient is φ = 1690791648.

The previous prime is 1721221087. The next prime is 1721221127. The reversal of 1721221111 is 1111221271.

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1721221111 is a prime.

It is a super-2 number, since 2×1721221111² = 5925204225904148642, 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 (1721224111) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 39736 + ... + 70861.

It is an arithmetic number, because the mean of its divisors is an integer number (218984040).

Almost surely, 2^1721221111 is an apocalyptic number.

1721221111 is a deficient number, since it is larger than the sum of its proper divisors (30651209).

1721221111 is a wasteful number, since it uses less digits than its factorization.

1721221111 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 110873.

The product of its digits is 56, while the sum is 19.

The square root of 1721221111 is about 41487.6018950240. The cubic root of 1721221111 is about 1198.4287562904.

Adding to 1721221111 its reverse (1111221271), we get a palindrome (2832442382).

The spelling of 1721221111 in words is "one billion, seven hundred twenty-one million, two hundred twenty-one thousand, one hundred eleven".