21056161 has 16 divisors (see below), whose sum is σ = 26152960. Its totient is φ = 16543440.

The previous prime is 21056159. The next prime is 21056171. The reversal of 21056161 is 16165012.

It is a cyclic number.

It is not a de Polignac number, because 21056161 - 2¹ = 21056159 is a prime.

It is an alternating number because its digits alternate between even and odd.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21056171) 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, 1570 + ... + 6676.

It is an arithmetic number, because the mean of its divisors is an integer number (1634560).

Almost surely, 2^21056161 is an apocalyptic number.

It is an amenable number.

21056161 is a deficient number, since it is larger than the sum of its proper divisors (5096799).

21056161 is a wasteful number, since it uses less digits than its factorization.

21056161 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5164.

The product of its (nonzero) digits is 360, while the sum is 22.

The square root of 21056161 is about 4588.6992710353. The cubic root of 21056161 is about 276.1381414819.

The spelling of 21056161 in words is "twenty-one million, fifty-six thousand, one hundred sixty-one".