81361663600 has 60 divisors (see below), whose sum is σ = 223395889744. Its totient is φ = 27895426560.

The previous prime is 81361663541. The next prime is 81361663613. The reversal of 81361663600 is 636616318.

It is a Harshad number since it is a multiple of its sum of digits (40).

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 14526069 + ... + 14531668.

Almost surely, 2^81361663600 is an apocalyptic number.

81361663600 is a gapful number since it is divisible by the number (80) formed by its first and last digit.

It is an amenable number.

81361663600 is an abundant number, since it is smaller than the sum of its proper divisors (142034226144).

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

81361663600 is a wasteful number, since it uses less digits than its factorization.

81361663600 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 29057762 (or 29057751 counting only the distinct ones).

The product of its (nonzero) digits is 93312, while the sum is 40.

The spelling of 81361663600 in words is "eighty-one billion, three hundred sixty-one million, six hundred sixty-three thousand, six hundred".