81623885 has 16 divisors (see below), whose sum is σ = 118526976. Its totient is φ = 52677888.

The previous prime is 81623881. The next prime is 81623903. The reversal of 81623885 is 58832618.

It is a cyclic number.

It is not a de Polignac number, because 81623885 - 2² = 81623881 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 (81623881) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 67997 + ... + 69186.

It is an arithmetic number, because the mean of its divisors is an integer number (7407936).

Almost surely, 2^81623885 is an apocalyptic number.

81623885 is a gapful number since it is divisible by the number (85) formed by its first and last digit.

It is an amenable number.

81623885 is a deficient number, since it is larger than the sum of its proper divisors (36903091).

81623885 is a wasteful number, since it uses less digits than its factorization.

81623885 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 137212.

The product of its digits is 92160, while the sum is 41.

The square root of 81623885 is about 9034.5937927502. The cubic root of 81623885 is about 433.7828927487.

The spelling of 81623885 in words is "eighty-one million, six hundred twenty-three thousand, eight hundred eighty-five".