81251446818 has 32 divisors (see below), whose sum is σ = 163266299136. Its totient is φ = 26956879488.

The previous prime is 81251446811. The next prime is 81251446891. The reversal of 81251446818 is 81864415218.

It is a super-2 number, since 2×81251446818² (a number of 23 digits) contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (81251446811) 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, 1066030 + ... + 1139702.

It is an arithmetic number, because the mean of its divisors is an integer number (5102071848).

Almost surely, 2^81251446818 is an apocalyptic number.

81251446818 is an abundant number, since it is smaller than the sum of its proper divisors (82014852318).

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

81251446818 is a wasteful number, since it uses less digits than its factorization.

81251446818 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 74538.

The product of its digits is 491520, while the sum is 48.

The spelling of 81251446818 in words is "eighty-one billion, two hundred fifty-one million, four hundred forty-six thousand, eight hundred eighteen".