81355659923 has 4 divisors (see below), whose sum is σ = 82689359328. Its totient is φ = 80021960520.

The previous prime is 81355659919. The next prime is 81355659929. The reversal of 81355659923 is 32995655318.

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 81355659923 - 2² = 81355659919 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (81355659929) 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, 666849611 + ... + 666849732.

It is an arithmetic number, because the mean of its divisors is an integer number (20672339832).

Almost surely, 2^81355659923 is an apocalyptic number.

81355659923 is a deficient number, since it is larger than the sum of its proper divisors (1333699405).

81355659923 is a wasteful number, since it uses less digits than its factorization.

81355659923 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1333699404.

The product of its digits is 8748000, while the sum is 56.

The spelling of 81355659923 in words is "eighty-one billion, three hundred fifty-five million, six hundred fifty-nine thousand, nine hundred twenty-three".