163813581 has 18 divisors (see below), whose sum is σ = 251361162. Its totient is φ = 102783360.

The previous prime is 163813571. The next prime is 163813583. The reversal of 163813581 is 185318361.

163813581 is a `hidden beast` number, since 1 + 63 + 8 + 13 + 581 = 666.

163813581 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It can be written as a sum of positive squares in 3 ways, for example, as 83997225 + 79816356 = 9165^2 + 8934^2 .

It is not a de Polignac number, because 163813581 - 2⁵ = 163813549 is a prime.

It is a super-2 number, since 2×163813581² = 53669778640087122, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (163813583) by changing a digit.

It is a polite number, since it can be written in 17 ways as a sum of consecutive naturals, for example, 28890 + ... + 34091.

It is an arithmetic number, because the mean of its divisors is an integer number (13964509).

Almost surely, 2^163813581 is an apocalyptic number.

It is an amenable number.

163813581 is a deficient number, since it is larger than the sum of its proper divisors (87547581).

163813581 is a wasteful number, since it uses less digits than its factorization.

163813581 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 63021 (or 63001 counting only the distinct ones).

The product of its digits is 17280, while the sum is 36.

The square root of 163813581 is about 12798.9679662073. The cubic root of 163813581 is about 547.1628899919.

The spelling of 163813581 in words is "one hundred sixty-three million, eight hundred thirteen thousand, five hundred eighty-one".