81197750 has 16 divisors (see below), whose sum is σ = 152002656. Its totient is φ = 32479000.

The previous prime is 81197689. The next prime is 81197759. The reversal of 81197750 is 5779118.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81197759) by changing a digit.

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 7 ways as a sum of consecutive naturals, for example, 162146 + ... + 162645.

It is an arithmetic number, because the mean of its divisors is an integer number (9500166).

Almost surely, 2^81197750 is an apocalyptic number.

81197750 is a deficient number, since it is larger than the sum of its proper divisors (70804906).

81197750 is a wasteful number, since it uses less digits than its factorization.

81197750 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 324808 (or 324798 counting only the distinct ones).

The product of its (nonzero) digits is 17640, while the sum is 38.

The square root of 81197750 is about 9010.9794140260. The cubic root of 81197750 is about 433.0266896985.

The spelling of 81197750 in words is "eighty-one million, one hundred ninety-seven thousand, seven hundred fifty".