43157981 has 2 divisors, whose sum is σ = 43157982. Its totient is φ = 43157980.

The previous prime is 43157963. The next prime is 43158023. The reversal of 43157981 is 18975134.

43157981 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 26429881 + 16728100 = 5141^2 + 4090^2 .

It is a cyclic number.

It is not a de Polignac number, because 43157981 - 2¹⁸ = 42895837 is a prime.

It is a super-2 number, since 2×43157981² = 3725222647992722, which contains 22 as substring.

It is a Sophie Germain 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 (43151981) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 21578990 + 21578991.

It is an arithmetic number, because the mean of its divisors is an integer number (21578991).

Almost surely, 2^43157981 is an apocalyptic number.

It is an amenable number.

43157981 is a deficient number, since it is larger than the sum of its proper divisors (1).

43157981 is an equidigital number, since it uses as much as digits as its factorization.

43157981 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 30240, while the sum is 38.

The square root of 43157981 is about 6569.4734187757. The cubic root of 43157981 is about 350.7683284392.

The spelling of 43157981 in words is "forty-three million, one hundred fifty-seven thousand, nine hundred eighty-one".