81442563553 has 8 divisors (see below), whose sum is σ = 87853320296. Its totient is φ = 75052656000.

The previous prime is 81442563533. The next prime is 81442563577. The reversal of 81442563553 is 35536524418.

It is a happy number.

It can be written as a sum of positive squares in 4 ways, for example, as 14977598689 + 66464964864 = 122383^2 + 257808^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 81442563553 - 2²⁹ = 80905692641 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (81442563523) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 5204178 + ... + 5219803.

It is an arithmetic number, because the mean of its divisors is an integer number (10981665037).

Almost surely, 2^81442563553 is an apocalyptic number.

It is an amenable number.

81442563553 is a deficient number, since it is larger than the sum of its proper divisors (6410756743).

81442563553 is a wasteful number, since it uses less digits than its factorization.

81442563553 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10424595.

The product of its digits is 1728000, while the sum is 46.

The spelling of 81442563553 in words is "eighty-one billion, four hundred forty-two million, five hundred sixty-three thousand, five hundred fifty-three".