1221011111 has 8 divisors (see below), whose sum is σ = 1293945840. Its totient is φ = 1148199808.

The previous prime is 1221011107. The next prime is 1221011177. The reversal of 1221011111 is 1111101221.

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 1221011111 - 2² = 1221011107 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 1221011092 and 1221011101.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1221011711) 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, 10076 + ... + 50433.

It is an arithmetic number, because the mean of its divisors is an integer number (161743230).

Almost surely, 2^1221011111 is an apocalyptic number.

1221011111 is a deficient number, since it is larger than the sum of its proper divisors (72934729).

1221011111 is a wasteful number, since it uses less digits than its factorization.

1221011111 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 61713.

The product of its (nonzero) digits is 4, while the sum is 11.

The square root of 1221011111 is about 34942.9694073071. The cubic root of 1221011111 is about 1068.8248404848.

Adding to 1221011111 its reverse (1111101221), we get a palindrome (2332112332).

The spelling of 1221011111 in words is "one billion, two hundred twenty-one million, eleven thousand, one hundred eleven".