81563193 has 24 divisors (see below), whose sum is σ = 124269600. Its totient is φ = 53444448.

The previous prime is 81563191. The next prime is 81563213. The reversal of 81563193 is 39136518.

It is a happy number.

81563193 is a `hidden beast` number, since 8 + 1 + 563 + 1 + 93 = 666.

It is not a de Polignac number, because 81563193 - 2¹ = 81563191 is a prime.

It is not an unprimeable number, because it can be changed into a prime (81563191) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 11493 + ... + 17181.

It is an arithmetic number, because the mean of its divisors is an integer number (5177900).

Almost surely, 2^81563193 is an apocalyptic number.

It is an amenable number.

81563193 is a deficient number, since it is larger than the sum of its proper divisors (42706407).

81563193 is an equidigital number, since it uses as much as digits as its factorization.

81563193 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5763 (or 5751 counting only the distinct ones).

The product of its digits is 19440, while the sum is 36.

The square root of 81563193 is about 9031.2343010244. The cubic root of 81563193 is about 433.6753520076.

The spelling of 81563193 in words is "eighty-one million, five hundred sixty-three thousand, one hundred ninety-three".