20013521 has 12 divisors (see below), whose sum is σ = 22138116. Its totient is φ = 18078720.

The previous prime is 20013491. The next prime is 20013523. The reversal of 20013521 is 12531002.

It is a happy number.

It can be written as a sum of positive squares in 2 ways, for example, as 12390400 + 7623121 = 3520^2 + 2761^2 .

It is not a de Polignac number, because 20013521 - 2²² = 15819217 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 20013496 and 20013505.

It is not an unprimeable number, because it can be changed into a prime (20013523) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 22925 + ... + 23781.

It is an arithmetic number, because the mean of its divisors is an integer number (1844843).

Almost surely, 2^20013521 is an apocalyptic number.

It is an amenable number.

20013521 is a deficient number, since it is larger than the sum of its proper divisors (2124595).

20013521 is a wasteful number, since it uses less digits than its factorization.

20013521 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1072 (or 1061 counting only the distinct ones).

The product of its (nonzero) digits is 60, while the sum is 14.

The square root of 20013521 is about 4473.6473933470. The cubic root of 20013521 is about 271.5029172811.

Adding to 20013521 its reverse (12531002), we get a palindrome (32544523).

The spelling of 20013521 in words is "twenty million, thirteen thousand, five hundred twenty-one".