81639048531 has 8 divisors (see below), whose sum is σ = 108871322560. Its totient is φ = 54416403432.

The previous prime is 81639048529. The next prime is 81639048577. The reversal of 81639048531 is 13584093618.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 81639048531 - 2¹ = 81639048529 is a prime.

It is a super-2 number, since 2×81639048531² (a number of 23 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (81639048521) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 2387425 + ... + 2421378.

It is an arithmetic number, because the mean of its divisors is an integer number (13608915320).

Almost surely, 2^81639048531 is an apocalyptic number.

81639048531 is a deficient number, since it is larger than the sum of its proper divisors (27232274029).

81639048531 is a wasteful number, since it uses less digits than its factorization.

81639048531 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4814465.

The product of its (nonzero) digits is 622080, while the sum is 48.

The spelling of 81639048531 in words is "eighty-one billion, six hundred thirty-nine million, forty-eight thousand, five hundred thirty-one".