11947981 has 2 divisors, whose sum is σ = 11947982. Its totient is φ = 11947980.

The previous prime is 11947973. The next prime is 11947993. The reversal of 11947981 is 18974911.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 7474756 + 4473225 = 2734^2 + 2115^2 .

It is a cyclic number.

It is not a de Polignac number, because 11947981 - 2³ = 11947973 is a prime.

It is a super-2 number, since 2×11947981² = 285508499952722, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (11947931) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5973990 + 5973991.

It is an arithmetic number, because the mean of its divisors is an integer number (5973991).

Almost surely, 2^11947981 is an apocalyptic number.

It is an amenable number.

11947981 is a deficient number, since it is larger than the sum of its proper divisors (1).

11947981 is an equidigital number, since it uses as much as digits as its factorization.

11947981 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 18144, while the sum is 40.

The square root of 11947981 is about 3456.5851645808. The cubic root of 11947981 is about 228.6115532795.

The spelling of 11947981 in words is "eleven million, nine hundred forty-seven thousand, nine hundred eighty-one".