81821442918 has 32 divisors (see below), whose sum is σ = 173336371200. Its totient is φ = 25659482240.

The previous prime is 81821442917. The next prime is 81821442929. The reversal of 81821442918 is 81924412818.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81821442917) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 109483 + ... + 419081.

It is an arithmetic number, because the mean of its divisors is an integer number (5416761600).

Almost surely, 2^81821442918 is an apocalyptic number.

81821442918 is an abundant number, since it is smaller than the sum of its proper divisors (91514928282).

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

81821442918 is a wasteful number, since it uses less digits than its factorization.

81821442918 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 312212.

The product of its digits is 294912, while the sum is 48.

The spelling of 81821442918 in words is "eighty-one billion, eight hundred twenty-one million, four hundred forty-two thousand, nine hundred eighteen".