81911903 has 2 divisors, whose sum is σ = 81911904. Its totient is φ = 81911902.

The previous prime is 81911887. The next prime is 81911923. The reversal of 81911903 is 30911918.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 81911903 - 2⁴ = 81911887 is a prime.

It is a super-3 number, since 3×81911903³ (a number of 25 digits) contains 333 as substring.

It is a Chen prime.

It is a self number, because there is not a number n which added to its sum of digits gives 81911903.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (81911923) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40955951 + 40955952.

It is an arithmetic number, because the mean of its divisors is an integer number (40955952).

Almost surely, 2^81911903 is an apocalyptic number.

81911903 is a deficient number, since it is larger than the sum of its proper divisors (1).

81911903 is an equidigital number, since it uses as much as digits as its factorization.

81911903 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1944, while the sum is 32.

The square root of 81911903 is about 9050.5194878526. The cubic root of 81911903 is about 434.2925091737.

The spelling of 81911903 in words is "eighty-one million, nine hundred eleven thousand, nine hundred three".