81368661618632 has 16 divisors (see below), whose sum is σ = 153105343862640. Its totient is φ = 40540569921936.

The previous prime is 81368661618631. The next prime is 81368661618679. The reversal of 81368661618632 is 23681616686318.

It is a happy number.

It is not an unprimeable number, because it can be changed into a prime (81368661618631) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 17970108518 + ... + 17970113045.

It is an arithmetic number, because the mean of its divisors is an integer number (9569083991415).

Almost surely, 2^{81368661618632} is an apocalyptic number.

It is an amenable number.

81368661618632 is a deficient number, since it is larger than the sum of its proper divisors (71736682244008).

81368661618632 is a wasteful number, since it uses less digits than its factorization.

81368661618632 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 35940221852 (or 35940221848 counting only the distinct ones).

The product of its digits is 71663616, while the sum is 65.

The spelling of 81368661618632 in words is "eighty-one trillion, three hundred sixty-eight billion, six hundred sixty-one million, six hundred eighteen thousand, six hundred thirty-two".