1220121191 has 4 divisors (see below), whose sum is σ = 1220200800. Its totient is φ = 1220041584.

The previous prime is 1220121169. The next prime is 1220121247. The reversal of 1220121191 is 1911210221.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length, and also an emirpimes, since its reverse is a distinct semiprime: 1911210221 = 131 ⋅14589391.

It is a cyclic number.

It is not a de Polignac number, because 1220121191 - 2²⁶ = 1153012327 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1220121151) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 8726 + ... + 50163.

It is an arithmetic number, because the mean of its divisors is an integer number (305050200).

Almost surely, 2^1220121191 is an apocalyptic number.

1220121191 is a deficient number, since it is larger than the sum of its proper divisors (79609).

1220121191 is an equidigital number, since it uses as much as digits as its factorization.

1220121191 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 79608.

The product of its (nonzero) digits is 72, while the sum is 20.

The square root of 1220121191 is about 34930.2331941829. The cubic root of 1220121191 is about 1068.5651104491.

The spelling of 1220121191 in words is "one billion, two hundred twenty million, one hundred twenty-one thousand, one hundred ninety-one".