81039641531 has 8 divisors (see below), whose sum is σ = 81097614720. Its totient is φ = 80981695168.

The previous prime is 81039641519. The next prime is 81039641533. The reversal of 81039641531 is 13514693018.

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-81039641531 is a prime.

It is a super-2 number, since 2×81039641531² (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 (81039641533) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 13438625 + ... + 13444653.

It is an arithmetic number, because the mean of its divisors is an integer number (10137201840).

Almost surely, 2^81039641531 is an apocalyptic number.

81039641531 is a deficient number, since it is larger than the sum of its proper divisors (57973189).

81039641531 is a wasteful number, since it uses less digits than its factorization.

81039641531 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 13413.

The product of its (nonzero) digits is 77760, while the sum is 41.

The spelling of 81039641531 in words is "eighty-one billion, thirty-nine million, six hundred forty-one thousand, five hundred thirty-one".