81461772288 has 288 divisors, whose sum is σ = 256490062920. Its totient is φ = 24763170816.

The previous prime is 81461772283. The next prime is 81461772289. The reversal of 81461772288 is 88227716418.

81461772288 is a `hidden beast` number, since 8 + 14 + 617 + 7 + 2 + 2 + 8 + 8 = 666.

It is a tau number, because it is divible by the number of its divisors (288).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81461772283) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 981467095 + ... + 981467177.

Almost surely, 2^81461772288 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 81461772288, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (128245031460).

81461772288 is an abundant number, since it is smaller than the sum of its proper divisors (175028290632).

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

81461772288 is an frugal number, since it uses more digits than its factorization.

81461772288 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 148 (or 101 counting only the distinct ones).

The product of its digits is 2408448, while the sum is 54.

The spelling of 81461772288 in words is "eighty-one billion, four hundred sixty-one million, seven hundred seventy-two thousand, two hundred eighty-eight".