81986197356 has 120 divisors (see below), whose sum is σ = 245238049056. Its totient is φ = 23396739840.

The previous prime is 81986197351. The next prime is 81986197367. The reversal of 81986197356 is 65379168918.

81986197356 is a `hidden beast` number, since 8 + 1 + 9 + 8 + 619 + 7 + 3 + 5 + 6 = 666.

It is a Harshad number since it is a multiple of its sum of digits (63).

It is a junction number, because it is equal to n+sod(n) for n = 81986197293 and 81986197302.

It is not an unprimeable number, because it can be changed into a prime (81986197351) 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 39 ways as a sum of consecutive naturals, for example, 1922586 + ... + 1964766.

Almost surely, 2^81986197356 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 81986197356, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (122619024528).

81986197356 is an abundant number, since it is smaller than the sum of its proper divisors (163251851700).

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

81986197356 is a wasteful number, since it uses less digits than its factorization.

81986197356 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 43061 (or 43050 counting only the distinct ones).

The product of its digits is 19595520, while the sum is 63.

The spelling of 81986197356 in words is "eighty-one billion, nine hundred eighty-six million, one hundred ninety-seven thousand, three hundred fifty-six".