81521175811 has 8 divisors (see below), whose sum is σ = 86660434224. Its totient is φ = 76420128000.

The previous prime is 81521175797. The next prime is 81521175847. The reversal of 81521175811 is 11857112518.

It is a happy number.

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

It is a cyclic number.

It is not a de Polignac number, because 81521175811 - 2¹⁵ = 81521143043 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (81521175011) 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, 9548250 + ... + 9556783.

It is an arithmetic number, because the mean of its divisors is an integer number (10832554278).

Almost surely, 2^81521175811 is an apocalyptic number.

81521175811 is a deficient number, since it is larger than the sum of its proper divisors (5139258413).

81521175811 is a wasteful number, since it uses less digits than its factorization.

81521175811 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 19105301.

The product of its digits is 22400, while the sum is 40.

The spelling of 81521175811 in words is "eighty-one billion, five hundred twenty-one million, one hundred seventy-five thousand, eight hundred eleven".