81805889088 has 840 divisors, whose sum is σ = 314975800832. Its totient is φ = 20528640000.

The previous prime is 81805889069. The next prime is 81805889107. The reversal of 81805889088 is 88098850818.

It is an interprime number because it is at equal distance from previous prime (81805889069) and next prime (81805889107).

It is a Harshad number since it is a multiple of its sum of digits (63).

It is an unprimeable number.

It is a polite number, since it can be written in 119 ways as a sum of consecutive naturals, for example, 136115988 + ... + 136116588.

Almost surely, 2^81805889088 is an apocalyptic number.

81805889088 is a gapful number since it is divisible by the number (88) 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 81805889088, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (157487900416).

81805889088 is an abundant number, since it is smaller than the sum of its proper divisors (233169911744).

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

81805889088 is a wasteful number, since it uses less digits than its factorization.

81805889088 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 685 (or 655 counting only the distinct ones).

The product of its (nonzero) digits is 11796480, while the sum is 63.

The spelling of 81805889088 in words is "eighty-one billion, eight hundred five million, eight hundred eighty-nine thousand, eighty-eight".