81370660 has 48 divisors (see below), whose sum is σ = 201600000. Its totient is φ = 26997120.

The previous prime is 81370651. The next prime is 81370699. The reversal of 81370660 is 6607318.

It is a Harshad number since it is a multiple of its sum of digits (31).

It is an unprimeable number.

It is a nontrivial repunit in base 433.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 5035 + ... + 13714.

It is an arithmetic number, because the mean of its divisors is an integer number (4200000).

Almost surely, 2^81370660 is an apocalyptic number.

It is an amenable number.

81370660 is an abundant number, since it is smaller than the sum of its proper divisors (120229340).

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

81370660 is a wasteful number, since it uses less digits than its factorization.

81370660 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 18796 (or 18794 counting only the distinct ones).

The product of its (nonzero) digits is 6048, while the sum is 31.

The square root of 81370660 is about 9020.5687182128. The cubic root of 81370660 is about 433.3338474682. Note that the first 3 decimals are identical.

Adding to 81370660 its reverse (6607318), we get a palindrome (87977978).

The spelling of 81370660 in words is "eighty-one million, three hundred seventy thousand, six hundred sixty".