12001981 has 2 divisors, whose sum is σ = 12001982. Its totient is φ = 12001980.

The previous prime is 12001963. The next prime is 12001987. The reversal of 12001981 is 18910021.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 11868025 + 133956 = 3445^2 + 366^2 .

It is a cyclic number.

It is not a de Polignac number, because 12001981 - 2¹⁵ = 11969213 is a prime.

It is a super-2 number, since 2×12001981² = 288095095848722, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (12001987) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 6000990 + 6000991.

It is an arithmetic number, because the mean of its divisors is an integer number (6000991).

Almost surely, 2^12001981 is an apocalyptic number.

It is an amenable number.

12001981 is a deficient number, since it is larger than the sum of its proper divisors (1).

12001981 is an equidigital number, since it uses as much as digits as its factorization.

12001981 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 144, while the sum is 22.

The square root of 12001981 is about 3464.3875360589. The cubic root of 12001981 is about 228.9554460337.

The spelling of 12001981 in words is "twelve million, one thousand, nine hundred eighty-one".