81180819261 has 12 divisors (see below), whose sum is σ = 117286829088. Its totient is φ = 54108709704.

The previous prime is 81180819259. The next prime is 81180819299. The reversal of 81180819261 is 16291808118.

It is not a de Polignac number, because 81180819261 - 2¹ = 81180819259 is a prime.

It is a super-2 number, since 2×81180819261² (a number of 23 digits) contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81180819361) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 942835 + ... + 1025328.

It is an arithmetic number, because the mean of its divisors is an integer number (9773902424).

Almost surely, 2^81180819261 is an apocalyptic number.

It is an amenable number.

81180819261 is a deficient number, since it is larger than the sum of its proper divisors (36106009827).

81180819261 is a wasteful number, since it uses less digits than its factorization.

81180819261 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1972752 (or 1972749 counting only the distinct ones).

The product of its (nonzero) digits is 55296, while the sum is 45.

The spelling of 81180819261 in words is "eighty-one billion, one hundred eighty million, eight hundred nineteen thousand, two hundred sixty-one".