81299052825 has 24 divisors (see below), whose sum is σ = 142321167648. Its totient is φ = 40808935680.

The previous prime is 81299052803. The next prime is 81299052841. The reversal of 81299052825 is 52825099218.

It is not a de Polignac number, because 81299052825 - 2⁶ = 81299052761 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (51).

It is an unprimeable number.

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 23 ways as a sum of consecutive naturals, for example, 31880707 + ... + 31883256.

It is an arithmetic number, because the mean of its divisors is an integer number (5930048652).

Almost surely, 2^81299052825 is an apocalyptic number.

81299052825 is a gapful number since it is divisible by the number (85) formed by its first and last digit.

It is an amenable number.

81299052825 is a deficient number, since it is larger than the sum of its proper divisors (61022114823).

81299052825 is a wasteful number, since it uses less digits than its factorization.

81299052825 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 63763993 (or 63763988 counting only the distinct ones).

The product of its (nonzero) digits is 1036800, while the sum is 51.

The spelling of 81299052825 in words is "eighty-one billion, two hundred ninety-nine million, fifty-two thousand, eight hundred twenty-five".