12127981 has 4 divisors (see below), whose sum is σ = 12333600. Its totient is φ = 11922364.

The previous prime is 12127967. The next prime is 12127991. The reversal of 12127981 is 18972121.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 18972121 = 7 ⋅2710303.

It is a cyclic number.

It is not a de Polignac number, because 12127981 - 2¹⁷ = 11996909 is a prime.

It is a super-2 number, since 2×12127981² = 294175846272722, which 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 (12127991) 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, 102721 + ... + 102838.

It is an arithmetic number, because the mean of its divisors is an integer number (3083400).

Almost surely, 2^12127981 is an apocalyptic number.

It is an amenable number.

12127981 is a deficient number, since it is larger than the sum of its proper divisors (205619).

12127981 is an equidigital number, since it uses as much as digits as its factorization.

12127981 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 205618.

The product of its digits is 2016, while the sum is 31.

The square root of 12127981 is about 3482.5250896440. The cubic root of 12127981 is about 229.7538702887.

The spelling of 12127981 in words is "twelve million, one hundred twenty-seven thousand, nine hundred eighty-one".