81205026660 has 96 divisors (see below), whose sum is σ = 253537401600. Its totient is φ = 21577570560.

The previous prime is 81205026653. The next prime is 81205026689. The reversal of 81205026660 is 6662050218.

It is a super-3 number, since 3×81205026660³ (a number of 34 digits) contains 333 as substring.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 115840 + ... + 419319.

It is an arithmetic number, because the mean of its divisors is an integer number (2641014600).

Almost surely, 2^81205026660 is an apocalyptic number.

It is an amenable number.

81205026660 is an abundant number, since it is smaller than the sum of its proper divisors (172332374940).

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

81205026660 is a wasteful number, since it uses less digits than its factorization.

81205026660 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 535458 (or 535450 counting only the distinct ones).

The product of its (nonzero) digits is 34560, while the sum is 36.

Adding to 81205026660 its reverse (6662050218), we get a palindrome (87867076878).

The spelling of 81205026660 in words is "eighty-one billion, two hundred five million, twenty-six thousand, six hundred sixty".