12011981 has 4 divisors (see below), whose sum is σ = 12028032. Its totient is φ = 11995932.

The previous prime is 12011977. The next prime is 12011983. The reversal of 12011981 is 18911021.

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: 18911021 = 17 ⋅1112413.

It is a cyclic number.

It is not a de Polignac number, because 12011981 - 2² = 12011977 is a prime.

It is a super-2 number, since 2×12011981² = 288575375088722, 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 (12011983) 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, 6845 + ... + 8418.

It is an arithmetic number, because the mean of its divisors is an integer number (3007008).

Almost surely, 2^12011981 is an apocalyptic number.

It is an amenable number.

12011981 is a deficient number, since it is larger than the sum of its proper divisors (16051).

12011981 is an equidigital number, since it uses as much as digits as its factorization.

12011981 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 16050.

The product of its (nonzero) digits is 144, while the sum is 23.

The square root of 12011981 is about 3465.8304921043. The cubic root of 12011981 is about 229.0190166190.

The spelling of 12011981 in words is "twelve million, eleven thousand, nine hundred eighty-one".