81541844465 has 32 divisors (see below), whose sum is σ = 99617541120. Its totient is φ = 64069056000.

The previous prime is 81541844389. The next prime is 81541844539. The reversal of 81541844465 is 56444814518.

It is a happy number.

It is not a de Polignac number, because 81541844465 - 2³⁰ = 80468102641 is a prime.

It is a super-2 number, since 2×81541844465² (a number of 23 digits) contains 22 as substring.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 28029431 + ... + 28032339.

It is an arithmetic number, because the mean of its divisors is an integer number (3113048160).

Almost surely, 2^81541844465 is an apocalyptic number.

It is an amenable number.

81541844465 is a deficient number, since it is larger than the sum of its proper divisors (18075696655).

81541844465 is a wasteful number, since it uses less digits than its factorization.

81541844465 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3473.

The product of its digits is 2457600, while the sum is 50.

The spelling of 81541844465 in words is "eighty-one billion, five hundred forty-one million, eight hundred forty-four thousand, four hundred sixty-five".