20481521 has 4 divisors (see below), whose sum is σ = 20491632. Its totient is φ = 20471412.

The previous prime is 20481497. The next prime is 20481533. The reversal of 20481521 is 12518402.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also a brilliant number, because the two primes have the same length.

It is a cyclic number.

It is not a de Polignac number, because 20481521 - 2¹⁸ = 20219377 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (20481541) 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, 851 + ... + 6456.

It is an arithmetic number, because the mean of its divisors is an integer number (5122908).

Almost surely, 2^20481521 is an apocalyptic number.

It is an amenable number.

20481521 is a deficient number, since it is larger than the sum of its proper divisors (10111).

20481521 is an equidigital number, since it uses as much as digits as its factorization.

20481521 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10110.

The product of its (nonzero) digits is 640, while the sum is 23.

The square root of 20481521 is about 4525.6514448199. The cubic root of 20481521 is about 273.6029244085.

Adding to 20481521 its reverse (12518402), we get a palindrome (32999923).

The spelling of 20481521 in words is "twenty million, four hundred eighty-one thousand, five hundred twenty-one".