20126521 has 4 divisors (see below), whose sum is σ = 21310452. Its totient is φ = 18942592.

The previous prime is 20126507. The next prime is 20126527. The reversal of 20126521 is 12562102.

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 18826921 + 1299600 = 4339^2 + 1140^2 .

It is a cyclic number.

It is not a de Polignac number, because 20126521 - 2⁵ = 20126489 is a prime.

It is not an unprimeable number, because it can be changed into a prime (20126527) 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, 591940 + ... + 591973.

It is an arithmetic number, because the mean of its divisors is an integer number (5327613).

Almost surely, 2^20126521 is an apocalyptic number.

It is an amenable number.

20126521 is a deficient number, since it is larger than the sum of its proper divisors (1183931).

20126521 is a wasteful number, since it uses less digits than its factorization.

20126521 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1183930.

The product of its (nonzero) digits is 240, while the sum is 19.

The square root of 20126521 is about 4486.2591320609. The cubic root of 20126521 is about 272.0129436242.

Adding to 20126521 its reverse (12562102), we get a palindrome (32688623).

The spelling of 20126521 in words is "twenty million, one hundred twenty-six thousand, five hundred twenty-one".