43778981 has 2 divisors, whose sum is σ = 43778982. Its totient is φ = 43778980.

The previous prime is 43778953. The next prime is 43778989. The reversal of 43778981 is 18987734.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 29528356 + 14250625 = 5434^2 + 3775^2 .

It is a cyclic number.

It is not a de Polignac number, because 43778981 - 2¹⁴ = 43762597 is a prime.

It is a super-2 number, since 2×43778981² = 3833198354796722, 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 (43778989) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 21889490 + 21889491.

It is an arithmetic number, because the mean of its divisors is an integer number (21889491).

Almost surely, 2^43778981 is an apocalyptic number.

It is an amenable number.

43778981 is a deficient number, since it is larger than the sum of its proper divisors (1).

43778981 is an equidigital number, since it uses as much as digits as its factorization.

43778981 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 338688, while the sum is 47.

The square root of 43778981 is about 6616.5686726581. The cubic root of 43778981 is about 352.4427242923.

The spelling of 43778981 in words is "forty-three million, seven hundred seventy-eight thousand, nine hundred eighty-one".