81441637564 has 72 divisors (see below), whose sum is σ = 170453393712. Its totient is φ = 33928392960.

The previous prime is 81441637517. The next prime is 81441637577. The reversal of 81441637564 is 46573614418.

It is a Harshad number since it is a multiple of its sum of digits (49).

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 2207679 + ... + 2244265.

It is an arithmetic number, because the mean of its divisors is an integer number (2367408246).

Almost surely, 2^81441637564 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 81441637564, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (85226696856).

81441637564 is an abundant number, since it is smaller than the sum of its proper divisors (89011756148).

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

81441637564 is a wasteful number, since it uses less digits than its factorization.

81441637564 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 36923 (or 36914 counting only the distinct ones).

The product of its digits is 1935360, while the sum is 49.

The spelling of 81441637564 in words is "eighty-one billion, four hundred forty-one million, six hundred thirty-seven thousand, five hundred sixty-four".