81485951561 has 4 divisors (see below), whose sum is σ = 93126801792. Its totient is φ = 69845101332.

The previous prime is 81485951537. The next prime is 81485951563. The reversal of 81485951561 is 16515958418.

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 a cyclic number.

It is not a de Polignac number, because 81485951561 - 2⁶ = 81485951497 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (81485951563) by changing a digit.

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 3 ways as a sum of consecutive naturals, for example, 5820425105 + ... + 5820425118.

It is an arithmetic number, because the mean of its divisors is an integer number (23281700448).

Almost surely, 2^81485951561 is an apocalyptic number.

It is an amenable number.

81485951561 is a deficient number, since it is larger than the sum of its proper divisors (11640850231).

81485951561 is a wasteful number, since it uses less digits than its factorization.

81485951561 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 11640850230.

The product of its digits is 1728000, while the sum is 53.

The spelling of 81485951561 in words is "eighty-one billion, four hundred eighty-five million, nine hundred fifty-one thousand, five hundred sixty-one".