81638805626880 has 896 divisors, whose sum is σ = 279299061619200. Its totient is φ = 20302931165184.

The previous prime is 81638805626879. The next prime is 81638805626881. The reversal of 81638805626880 is 8862650883618.

It is an interprime number because it is at equal distance from previous prime (81638805626879) and next prime (81638805626881).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81638805626881) by changing a digit.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 43218000976 + ... + 43218002864.

It is an arithmetic number, because the mean of its divisors is an integer number (311717702700).

Almost surely, 2^{81638805626880} is an apocalyptic number.

81638805626880 is a gapful number since it is divisible by the number (80) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 81638805626880, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (139649530809600).

81638805626880 is an abundant number, since it is smaller than the sum of its proper divisors (197660255992320).

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

81638805626880 is a wasteful number, since it uses less digits than its factorization.

81638805626880 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2222 (or 2198 counting only the distinct ones).

The product of its (nonzero) digits is 212336640, while the sum is 69.

The spelling of 81638805626880 in words is "eighty-one trillion, six hundred thirty-eight billion, eight hundred five million, six hundred twenty-six thousand, eight hundred eighty".