81638870450 has 24 divisors (see below), whose sum is σ = 156746634240. Its totient is φ = 31602142800.

The previous prime is 81638870447. The next prime is 81638870477. The reversal of 81638870450 is 5407883618.

It is a Smith number, since the sum of its digits (50) coincides with the sum of the digits of its prime factors.

It is a Harshad number since it is a multiple of its sum of digits (50).

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 26333570 + ... + 26336669.

It is an arithmetic number, because the mean of its divisors is an integer number (6531109760).

Almost surely, 2^81638870450 is an apocalyptic number.

81638870450 is a deficient number, since it is larger than the sum of its proper divisors (75107763790).

81638870450 is a wasteful number, since it uses less digits than its factorization.

81638870450 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 52670282 (or 52670277 counting only the distinct ones).

The product of its (nonzero) digits is 1290240, while the sum is 50.

The spelling of 81638870450 in words is "eighty-one billion, six hundred thirty-eight million, eight hundred seventy thousand, four hundred fifty".