81638826 has 8 divisors (see below), whose sum is σ = 163277664. Its totient is φ = 27212940.

The previous prime is 81638813. The next prime is 81638861. The reversal of 81638826 is 62883618.

It is a sphenic number, since it is the product of 3 distinct primes.

81638826 is an admirable number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 6803230 + ... + 6803241.

It is an arithmetic number, because the mean of its divisors is an integer number (20409708).

Almost surely, 2^81638826 is an apocalyptic number.

81638826 is a primitive abundant number, since it is smaller than the sum of its proper divisors, none of which is abundant.

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

81638826 is a wasteful number, since it uses less digits than its factorization.

81638826 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 13606476.

The product of its digits is 110592, while the sum is 42.

The square root of 81638826 is about 9035.4206321565. The cubic root of 81638826 is about 433.8093586735.

The spelling of 81638826 in words is "eighty-one million, six hundred thirty-eight thousand, eight hundred twenty-six".