81211154144 has 24 divisors (see below), whose sum is σ = 159899300568. Its totient is φ = 40601808000.

The previous prime is 81211154071. The next prime is 81211154173. The reversal of 81211154144 is 44145111218.

It is a Harshad number since it is a multiple of its sum of digits (32).

It is a self number, because there is not a number n which added to its sum of digits gives 81211154144.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 250019 + ... + 474269.

It is an arithmetic number, because the mean of its divisors is an integer number (6662470857).

Almost surely, 2^81211154144 is an apocalyptic number.

It is an amenable number.

81211154144 is a deficient number, since it is larger than the sum of its proper divisors (78688146424).

81211154144 is a wasteful number, since it uses less digits than its factorization.

81211154144 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 235578 (or 235570 counting only the distinct ones).

The product of its digits is 5120, while the sum is 32.

The spelling of 81211154144 in words is "eighty-one billion, two hundred eleven million, one hundred fifty-four thousand, one hundred forty-four".