81606623 has 4 divisors (see below), whose sum is σ = 93264720. Its totient is φ = 69948528.

The previous prime is 81606611. The next prime is 81606631. The reversal of 81606623 is 32660618.

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

It is a cyclic number.

It is not a de Polignac number, because 81606623 - 2⁴ = 81606607 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 81606623.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81606643) 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, 5829038 + ... + 5829051.

It is an arithmetic number, because the mean of its divisors is an integer number (23316180).

Almost surely, 2^81606623 is an apocalyptic number.

81606623 is a deficient number, since it is larger than the sum of its proper divisors (11658097).

81606623 is a wasteful number, since it uses less digits than its factorization.

81606623 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 11658096.

The product of its (nonzero) digits is 10368, while the sum is 32.

The square root of 81606623 is about 9033.6384142825. The cubic root of 81606623 is about 433.7523114705.

The spelling of 81606623 in words is "eighty-one million, six hundred six thousand, six hundred twenty-three".