81812269440 has 192 divisors, whose sum is σ = 308190776400. Its totient is φ = 19833262080.

The previous prime is 81812269397. The next prime is 81812269457. The reversal of 81812269440 is 4496221818.

81812269440 is a `hidden beast` number, since 8 + 181 + 2 + 26 + 9 + 440 = 666.

It is a tau number, because it is divible by the number of its divisors (192).

It is a Harshad number since it is a multiple of its sum of digits (45).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 582255 + ... + 708974.

Almost surely, 2^81812269440 is an apocalyptic number.

81812269440 is a gapful number since it is divisible by the number (80) formed by its first and last digit.

It is an amenable number.

81812269440 is an abundant number, since it is smaller than the sum of its proper divisors (226378506960).

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

81812269440 is a wasteful number, since it uses less digits than its factorization.

81812269440 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1291265 (or 1291250 counting only the distinct ones).

The product of its (nonzero) digits is 221184, while the sum is 45.

The spelling of 81812269440 in words is "eighty-one billion, eight hundred twelve million, two hundred sixty-nine thousand, four hundred forty".