43921991 has 2 divisors, whose sum is σ = 43921992. Its totient is φ = 43921990.

The previous prime is 43921987. The next prime is 43921993. The reversal of 43921991 is 19912934.

43921991 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 43921991 - 2² = 43921987 is a prime.

Together with 43921993, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (43921993) 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, 21960995 + 21960996.

It is an arithmetic number, because the mean of its divisors is an integer number (21960996).

Almost surely, 2^43921991 is an apocalyptic number.

43921991 is a deficient number, since it is larger than the sum of its proper divisors (1).

43921991 is an equidigital number, since it uses as much as digits as its factorization.

43921991 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 17496, while the sum is 38.

The square root of 43921991 is about 6627.3668225020. The cubic root of 43921991 is about 352.8260745490.

The spelling of 43921991 in words is "forty-three million, nine hundred twenty-one thousand, nine hundred ninety-one".