81564481061 has 4 divisors (see below), whose sum is σ = 93216549792. Its totient is φ = 69912412332.

The previous prime is 81564481057. The next prime is 81564481073. The reversal of 81564481061 is 16018446518.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is not a de Polignac number, because 81564481061 - 2² = 81564481057 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81564481001) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 5826034355 + ... + 5826034368.

It is an arithmetic number, because the mean of its divisors is an integer number (23304137448).

Almost surely, 2^81564481061 is an apocalyptic number.

It is an amenable number.

81564481061 is a deficient number, since it is larger than the sum of its proper divisors (11652068731).

81564481061 is a wasteful number, since it uses less digits than its factorization.

81564481061 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 11652068730.

The product of its (nonzero) digits is 184320, while the sum is 44.

The spelling of 81564481061 in words is "eighty-one billion, five hundred sixty-four million, four hundred eighty-one thousand, sixty-one".