81521175311 has 2 divisors, whose sum is σ = 81521175312. Its totient is φ = 81521175310.

The previous prime is 81521175289. The next prime is 81521175313. The reversal of 81521175311 is 11357112518.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-81521175311 is a prime.

It is a Sophie Germain prime.

Together with 81521175313, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (81521175313) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40760587655 + 40760587656.

It is an arithmetic number, because the mean of its divisors is an integer number (40760587656).

Almost surely, 2^81521175311 is an apocalyptic number.

81521175311 is a deficient number, since it is larger than the sum of its proper divisors (1).

81521175311 is an equidigital number, since it uses as much as digits as its factorization.

81521175311 is an evil number, because the sum of its binary digits is even.

The product of its digits is 8400, while the sum is 35.

Adding to 81521175311 its reverse (11357112518), we get a palindrome (92878287829).

The spelling of 81521175311 in words is "eighty-one billion, five hundred twenty-one million, one hundred seventy-five thousand, three hundred eleven".