21056145 has 32 divisors (see below), whose sum is σ = 37756800. Its totient is φ = 9930240.

The previous prime is 21056143. The next prime is 21056153. The reversal of 21056145 is 54165012.

It is not a de Polignac number, because 21056145 - 2¹ = 21056143 is a prime.

It is a super-2 number, since 2×21056145² = 886722484522050, which contains 22 as substring.

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

It is not an unprimeable number, because it can be changed into a prime (21056143) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 4381 + ... + 7829.

It is an arithmetic number, because the mean of its divisors is an integer number (1179900).

Almost surely, 2^21056145 is an apocalyptic number.

It is an amenable number.

21056145 is a deficient number, since it is larger than the sum of its proper divisors (16700655).

21056145 is a wasteful number, since it uses less digits than its factorization.

21056145 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3505.

The product of its (nonzero) digits is 1200, while the sum is 24.

The square root of 21056145 is about 4588.6975276215. The cubic root of 21056145 is about 276.1380715386.

The spelling of 21056145 in words is "twenty-one million, fifty-six thousand, one hundred forty-five".