20313521 has 6 divisors (see below), whose sum is σ = 21579030. Its totient is φ = 19118336.

The previous prime is 20313511. The next prime is 20313563. The reversal of 20313521 is 12531302.

It can be written as a sum of positive squares in 3 ways, for example, as 15295921 + 5017600 = 3911^2 + 2240^2 .

It is not a de Polignac number, because 20313521 - 2¹⁰ = 20312497 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (17).

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 20313521.

It is not an unprimeable number, because it can be changed into a prime (20313511) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 34856 + ... + 35433.

It is an arithmetic number, because the mean of its divisors is an integer number (3596505).

Almost surely, 2^20313521 is an apocalyptic number.

It is an amenable number.

20313521 is a deficient number, since it is larger than the sum of its proper divisors (1265509).

20313521 is an equidigital number, since it uses as much as digits as its factorization.

20313521 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 70323 (or 70306 counting only the distinct ones).

The product of its (nonzero) digits is 180, while the sum is 17.

The square root of 20313521 is about 4507.0523626867. The cubic root of 20313521 is about 272.8527922256.

Adding to 20313521 its reverse (12531302), we get a palindrome (32844823).

The spelling of 20313521 in words is "twenty million, three hundred thirteen thousand, five hundred twenty-one".