81529918 has 4 divisors (see below), whose sum is σ = 122294880. Its totient is φ = 40764958.

The previous prime is 81529891. The next prime is 81529919. The reversal of 81529918 is 81992518.

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

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81529919) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 20382478 + ... + 20382481.

It is an arithmetic number, because the mean of its divisors is an integer number (30573720).

Almost surely, 2^81529918 is an apocalyptic number.

81529918 is a deficient number, since it is larger than the sum of its proper divisors (40764962).

81529918 is a wasteful number, since it uses less digits than its factorization.

81529918 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 40764961.

The product of its digits is 51840, while the sum is 43.

The square root of 81529918 is about 9029.3918953604. The cubic root of 81529918 is about 433.6163690699.

The spelling of 81529918 in words is "eighty-one million, five hundred twenty-nine thousand, nine hundred eighteen".