11989781 has 2 divisors, whose sum is σ = 11989782. Its totient is φ = 11989780.

The previous prime is 11989763. The next prime is 11989793. The reversal of 11989781 is 18798911.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 11115556 + 874225 = 3334^2 + 935^2 .

It is a cyclic number.

It is not a de Polignac number, because 11989781 - 2¹⁴ = 11973397 is a prime.

It is a super-2 number, since 2×11989781² = 287509696855922, which contains 22 as substring.

It is a Sophie Germain prime.

It is a Chen prime.

It is a Curzon number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (11989721) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5994890 + 5994891.

It is an arithmetic number, because the mean of its divisors is an integer number (5994891).

Almost surely, 2^11989781 is an apocalyptic number.

It is an amenable number.

11989781 is a deficient number, since it is larger than the sum of its proper divisors (1).

11989781 is an equidigital number, since it uses as much as digits as its factorization.

11989781 is an evil number, because the sum of its binary digits is even.

The product of its digits is 36288, while the sum is 44.

The square root of 11989781 is about 3462.6263153855. The cubic root of 11989781 is about 228.8778420830.

The spelling of 11989781 in words is "eleven million, nine hundred eighty-nine thousand, seven hundred eighty-one".