81000418464 has 72 divisors (see below), whose sum is σ = 263251366560. Its totient is φ = 23142976128.

The previous prime is 81000418363. The next prime is 81000418573. The reversal of 81000418464 is 46481400018.

It is a tau number, because it is divible by the number of its divisors (72).

It is a super-2 number, since 2×81000418464² (a number of 23 digits) contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (36).

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, 20087374 + ... + 20091405.

It is an arithmetic number, because the mean of its divisors is an integer number (3656268980).

Almost surely, 2^81000418464 is an apocalyptic number.

81000418464 is a gapful number since it is divisible by the number (84) formed by its first and last digit.

It is an amenable number.

81000418464 is an abundant number, since it is smaller than the sum of its proper divisors (182250948096).

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

81000418464 is a wasteful number, since it uses less digits than its factorization.

81000418464 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 40178802 (or 40178791 counting only the distinct ones).

The product of its (nonzero) digits is 24576, while the sum is 36.

The spelling of 81000418464 in words is "eighty-one billion, four hundred eighteen thousand, four hundred sixty-four".