81249943 has 2 divisors, whose sum is σ = 81249944. Its totient is φ = 81249942.

The previous prime is 81249941. The next prime is 81249979. The reversal of 81249943 is 34994218.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 81249943 - 2¹ = 81249941 is a prime.

It is a super-3 number, since 3×81249943³ (a number of 25 digits) contains 333 as substring.

Together with 81249941, it forms a pair of twin primes.

It is a junction number, because it is equal to n+sod(n) for n = 81249896 and 81249905.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (81249941) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40624971 + 40624972.

It is an arithmetic number, because the mean of its divisors is an integer number (40624972).

Almost surely, 2^81249943 is an apocalyptic number.

81249943 is a deficient number, since it is larger than the sum of its proper divisors (1).

81249943 is an equidigital number, since it uses as much as digits as its factorization.

81249943 is an evil number, because the sum of its binary digits is even.

The product of its digits is 62208, while the sum is 40.

The square root of 81249943 is about 9013.8750268683. The cubic root of 81249943 is about 433.1194513871.

The spelling of 81249943 in words is "eighty-one million, two hundred forty-nine thousand, nine hundred forty-three".