20404521 has 16 divisors (see below), whose sum is σ = 30299520. Its totient is φ = 13571280.

The previous prime is 20404493. The next prime is 20404547. The reversal of 20404521 is 12540402.

It is not a de Polignac number, because 20404521 - 2⁷ = 20404393 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 20404494 and 20404503.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20404591) 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 15 ways as a sum of consecutive naturals, for example, 19276 + ... + 20306.

It is an arithmetic number, because the mean of its divisors is an integer number (1893720).

Almost surely, 2^20404521 is an apocalyptic number.

It is an amenable number.

20404521 is a deficient number, since it is larger than the sum of its proper divisors (9894999).

20404521 is a wasteful number, since it uses less digits than its factorization.

20404521 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1773 (or 1767 counting only the distinct ones).

The product of its (nonzero) digits is 320, while the sum is 18.

The square root of 20404521 is about 4517.1363716408. The cubic root of 20404521 is about 273.2596250126.

Adding to 20404521 its reverse (12540402), we get a palindrome (32944923).

It can be divided in two parts, 2040 and 4521, that added together give a 8-th power (6561 = 3⁸).

The spelling of 20404521 in words is "twenty million, four hundred four thousand, five hundred twenty-one".