81549069531 has 8 divisors (see below), whose sum is σ = 108751773504. Its totient is φ = 54356205960.

The previous prime is 81549069523. The next prime is 81549069611. The reversal of 81549069531 is 13596094518.

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

It is not a de Polignac number, because 81549069531 - 2³ = 81549069523 is a prime.

It is a super-2 number, since 2×81549069531² (a number of 23 digits) contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (81549079531) 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, 2440741 + ... + 2473926.

It is an arithmetic number, because the mean of its divisors is an integer number (13593971688).

Almost surely, 2^81549069531 is an apocalyptic number.

81549069531 is a deficient number, since it is larger than the sum of its proper divisors (27202703973).

81549069531 is a wasteful number, since it uses less digits than its factorization.

81549069531 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4920201.

The product of its (nonzero) digits is 1166400, while the sum is 51.

The spelling of 81549069531 in words is "eighty-one billion, five hundred forty-nine million, sixty-nine thousand, five hundred thirty-one".