81439903 has 2 divisors, whose sum is σ = 81439904. Its totient is φ = 81439902.

The previous prime is 81439901. The next prime is 81439931. The reversal of 81439903 is 30993418.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 81439903 - 2¹ = 81439901 is a prime.

Together with 81439901, it forms a pair of twin primes.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (81439901) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40719951 + 40719952.

It is an arithmetic number, because the mean of its divisors is an integer number (40719952).

Almost surely, 2^81439903 is an apocalyptic number.

81439903 is a deficient number, since it is larger than the sum of its proper divisors (1).

81439903 is an equidigital number, since it uses as much as digits as its factorization.

81439903 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 23328, while the sum is 37.

The square root of 81439903 is about 9024.4059638294. The cubic root of 81439903 is about 433.4567288955.

The spelling of 81439903 in words is "eighty-one million, four hundred thirty-nine thousand, nine hundred three".