81619903 has 4 divisors (see below), whose sum is σ = 81776488. Its totient is φ = 81463320.

The previous prime is 81619849. The next prime is 81619919. The reversal of 81619903 is 30991618.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-81619903 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81619103) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 77508 + ... + 78553.

It is an arithmetic number, because the mean of its divisors is an integer number (20444122).

Almost surely, 2^81619903 is an apocalyptic number.

81619903 is a deficient number, since it is larger than the sum of its proper divisors (156585).

81619903 is a wasteful number, since it uses less digits than its factorization.

81619903 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 156584.

The product of its (nonzero) digits is 11664, while the sum is 37.

The square root of 81619903 is about 9034.3734149082. The cubic root of 81619903 is about 433.7758386388.

The spelling of 81619903 in words is "eighty-one million, six hundred nineteen thousand, nine hundred three".