81638635050 has 384 divisors, whose sum is σ = 272993241600. Its totient is φ = 17512796160.

The previous prime is 81638634991. The next prime is 81638635081. The reversal of 81638635050 is 5053683618.

81638635050 is a `hidden beast` number, since 8 + 1 + 6 + 3 + 8 + 635 + 0 + 5 + 0 = 666.

It is a Harshad number since it is a multiple of its sum of digits (45).

It is a junction number, because it is equal to n+sod(n) for n = 81638634987 and 81638635005.

It is an unprimeable number.

It is a polite number, since it can be written in 191 ways as a sum of consecutive naturals, for example, 98478036 + ... + 98478864.

It is an arithmetic number, because the mean of its divisors is an integer number (710919900).

Almost surely, 2^81638635050 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 81638635050, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (136496620800).

81638635050 is an abundant number, since it is smaller than the sum of its proper divisors (191354606550).

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

81638635050 is a wasteful number, since it uses less digits than its factorization.

81638635050 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1487 (or 1476 counting only the distinct ones).

The product of its (nonzero) digits is 518400, while the sum is 45.

The spelling of 81638635050 in words is "eighty-one billion, six hundred thirty-eight million, six hundred thirty-five thousand, fifty".