11971987 has 2 divisors, whose sum is σ = 11971988. Its totient is φ = 11971986.

The previous prime is 11971943. The next prime is 11971991. The reversal of 11971987 is 78917911.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 11971987 - 2¹⁹ = 11447699 is a prime.

It is not a weakly prime, because it can be changed into another prime (11971087) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5985993 + 5985994.

It is an arithmetic number, because the mean of its divisors is an integer number (5985994).

Almost surely, 2^11971987 is an apocalyptic number.

11971987 is a deficient number, since it is larger than the sum of its proper divisors (1).

11971987 is an equidigital number, since it uses as much as digits as its factorization.

11971987 is an evil number, because the sum of its binary digits is even.

The product of its digits is 31752, while the sum is 43.

The square root of 11971987 is about 3460.0559244035. The cubic root of 11971987 is about 228.7645603719.

The spelling of 11971987 in words is "eleven million, nine hundred seventy-one thousand, nine hundred eighty-seven".