21524201 has 4 divisors (see below), whose sum is σ = 21930372. Its totient is φ = 21118032.

The previous prime is 21524189. The next prime is 21524231. The reversal of 21524201 is 10242512.

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 10896601 + 10627600 = 3301^2 + 3260^2 .

It is a cyclic number.

It is not a de Polignac number, because 21524201 - 2¹⁸ = 21262057 is a prime.

It is a Duffinian number.

It is a plaindrome in base 9.

It is a self number, because there is not a number n which added to its sum of digits gives 21524201.

It is not an unprimeable number, because it can be changed into a prime (21524231) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 203006 + ... + 203111.

It is an arithmetic number, because the mean of its divisors is an integer number (5482593).

Almost surely, 2^21524201 is an apocalyptic number.

It is an amenable number.

21524201 is a deficient number, since it is larger than the sum of its proper divisors (406171).

21524201 is an equidigital number, since it uses as much as digits as its factorization.

21524201 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 406170.

The product of its (nonzero) digits is 160, while the sum is 17.

The square root of 21524201 is about 4639.4181747284. The cubic root of 21524201 is about 278.1691817367.

Adding to 21524201 its reverse (10242512), we get a palindrome (31766713).

The spelling of 21524201 in words is "twenty-one million, five hundred twenty-four thousand, two hundred one".