21552145 has 4 divisors (see below), whose sum is σ = 25862580. Its totient is φ = 17241712.

The previous prime is 21552143. The next prime is 21552197. The reversal of 21552145 is 54125512.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 9168784 + 12383361 = 3028^2 + 3519^2 .

It is a cyclic number.

It is not a de Polignac number, because 21552145 - 2¹ = 21552143 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21552143) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2155210 + ... + 2155219.

It is an arithmetic number, because the mean of its divisors is an integer number (6465645).

Almost surely, 2^21552145 is an apocalyptic number.

It is an amenable number.

21552145 is a deficient number, since it is larger than the sum of its proper divisors (4310435).

21552145 is an equidigital number, since it uses as much as digits as its factorization.

21552145 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4310434.

The product of its digits is 2000, while the sum is 25.

The square root of 21552145 is about 4642.4287824371. The cubic root of 21552145 is about 278.2895082811.

Adding to 21552145 its reverse (54125512), we get a palindrome (75677657).

The spelling of 21552145 in words is "twenty-one million, five hundred fifty-two thousand, one hundred forty-five".