1221111091 has 16 divisors (see below), whose sum is σ = 1274565600. Its totient is φ = 1168473600.

The previous prime is 1221111083. The next prime is 1221111097. The reversal of 1221111091 is 1901111221.

It is a cyclic number.

It is not a de Polignac number, because 1221111091 - 2³ = 1221111083 is a prime.

It is a super-2 number, since 2×1221111091² = 2982224593126420562, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1221111097) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 2648601 + ... + 2649061.

It is an arithmetic number, because the mean of its divisors is an integer number (79660350).

Almost surely, 2^1221111091 is an apocalyptic number.

1221111091 is a deficient number, since it is larger than the sum of its proper divisors (53454509).

1221111091 is a wasteful number, since it uses less digits than its factorization.

1221111091 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1110.

The product of its (nonzero) digits is 36, while the sum is 19.

The square root of 1221111091 is about 34944.3999948490. The cubic root of 1221111091 is about 1068.8540125347.

The spelling of 1221111091 in words is "one billion, two hundred twenty-one million, one hundred eleven thousand, ninety-one".