81948985529 has 4 divisors (see below), whose sum is σ = 83172104784. Its totient is φ = 80725866276.

The previous prime is 81948985511. The next prime is 81948985541. The reversal of 81948985529 is 92558984918.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 81948985529 - 2²⁸ = 81680550073 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (81948985589) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 611559527 + ... + 611559660.

It is an arithmetic number, because the mean of its divisors is an integer number (20793026196).

Almost surely, 2^81948985529 is an apocalyptic number.

It is an amenable number.

81948985529 is a deficient number, since it is larger than the sum of its proper divisors (1223119255).

81948985529 is a wasteful number, since it uses less digits than its factorization.

81948985529 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1223119254.

The product of its digits is 74649600, while the sum is 68.

The spelling of 81948985529 in words is "eighty-one billion, nine hundred forty-eight million, nine hundred eighty-five thousand, five hundred twenty-nine".