1221002688181 has 4 divisors (see below), whose sum is σ = 1221225626412. Its totient is φ = 1220779749952.

The previous prime is 1221002688151. The next prime is 1221002688229. The reversal of 1221002688181 is 1818862001221.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 624362307556 + 596640380625 = 790166^2 + 772425^2 .

It is a cyclic number.

It is not a de Polignac number, because 1221002688181 - 2³¹ = 1218855204533 is a prime.

It is a super-2 number, since 2×1221002688181² (a number of 25 digits) 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 (1221002688151) 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, 111460900 + ... + 111471853.

It is an arithmetic number, because the mean of its divisors is an integer number (305306406603).

Almost surely, 2^{1221002688181} is an apocalyptic number.

It is an amenable number.

1221002688181 is a deficient number, since it is larger than the sum of its proper divisors (222938231).

1221002688181 is an equidigital number, since it uses as much as digits as its factorization.

1221002688181 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 222938230.

The product of its (nonzero) digits is 24576, while the sum is 40.

The spelling of 1221002688181 in words is "one trillion, two hundred twenty-one billion, two million, six hundred eighty-eight thousand, one hundred eighty-one".