81538740252 has 36 divisors (see below), whose sum is σ = 206127304656. Its totient is φ = 27177537600.

The previous prime is 81538740251. The next prime is 81538740259. The reversal of 81538740252 is 25204783518.

81538740252 is a `hidden beast` number, since 8 + 15 + 387 + 4 + 0 + 252 = 666.

It is a tau number, because it is divible by the number of its divisors (36).

It is a junction number, because it is equal to n+sod(n) for n = 81538740198 and 81538740207.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81538740251) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 446008 + ... + 601664.

Almost surely, 2^81538740252 is an apocalyptic number.

It is an amenable number.

81538740252 is an abundant number, since it is smaller than the sum of its proper divisors (124588564404).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

81538740252 is a wasteful number, since it uses less digits than its factorization.

81538740252 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 170218 (or 170213 counting only the distinct ones).

The product of its (nonzero) digits is 537600, while the sum is 45.

The spelling of 81538740252 in words is "eighty-one billion, five hundred thirty-eight million, seven hundred forty thousand, two hundred fifty-two".