163561021 has 16 divisors (see below), whose sum is σ = 180324144. Its totient is φ = 147423744.

The previous prime is 163561019. The next prime is 163561033. The reversal of 163561021 is 120165361.

It can be written as a sum of positive squares in 8 ways, for example, as 2500 + 163558521 = 50^2 + 12789^2 .

It is not a de Polignac number, because 163561021 - 2¹ = 163561019 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (163561001) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 190425 + ... + 191281.

It is an arithmetic number, because the mean of its divisors is an integer number (11270259).

Almost surely, 2^163561021 is an apocalyptic number.

It is an amenable number.

163561021 is a deficient number, since it is larger than the sum of its proper divisors (16763123).

163561021 is a wasteful number, since it uses less digits than its factorization.

163561021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1200.

The product of its (nonzero) digits is 1080, while the sum is 25.

The square root of 163561021 is about 12789.0977398720. The cubic root of 163561021 is about 546.8815487695.

The spelling of 163561021 in words is "one hundred sixty-three million, five hundred sixty-one thousand, twenty-one".