81171202180 has 24 divisors (see below), whose sum is σ = 170465886360. Its totient is φ = 32467269120.

The previous prime is 81171202171. The next prime is 81171202207. The reversal of 81171202180 is 8120217118.

It can be written as a sum of positive squares in 4 ways, for example, as 21252974656 + 59918227524 = 145784^2 + 244782^2 .

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 637276 + ... + 753964.

It is an arithmetic number, because the mean of its divisors is an integer number (7102745265).

Almost surely, 2^81171202180 is an apocalyptic number.

It is an amenable number.

81171202180 is an abundant number, since it is smaller than the sum of its proper divisors (89294684180).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

81171202180 is a wasteful number, since it uses less digits than its factorization.

81171202180 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 151479 (or 151477 counting only the distinct ones).

The product of its (nonzero) digits is 1792, while the sum is 31.

Adding to 81171202180 its reverse (8120217118), we get a palindrome (89291419298).

The spelling of 81171202180 in words is "eighty-one billion, one hundred seventy-one million, two hundred two thousand, one hundred eighty".