1220121989 has 4 divisors (see below), whose sum is σ = 1220232780. Its totient is φ = 1220011200.

The previous prime is 1220121967. The next prime is 1220122003. The reversal of 1220121989 is 9891210221.

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: 9891210221 = 491 ⋅20145031.

It can be written as a sum of positive squares in 2 ways, for example, as 169260100 + 1050861889 = 13010^2 + 32417^2 .

It is a cyclic number.

It is not a de Polignac number, because 1220121989 - 2²⁰ = 1219073413 is a prime.

It is a super-2 number, since 2×1220121989² = 2977395336082632242, which contains 22 as substring.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1220120989) 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, 36794 + ... + 61595.

It is an arithmetic number, because the mean of its divisors is an integer number (305058195).

Almost surely, 2^1220121989 is an apocalyptic number.

It is an amenable number.

1220121989 is a deficient number, since it is larger than the sum of its proper divisors (110791).

1220121989 is an equidigital number, since it uses as much as digits as its factorization.

1220121989 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 110790.

The product of its (nonzero) digits is 5184, while the sum is 35.

The square root of 1220121989 is about 34930.2446169505. The cubic root of 1220121989 is about 1068.5653434081.

The spelling of 1220121989 in words is "one billion, two hundred twenty million, one hundred twenty-one thousand, nine hundred eighty-nine".