20513556 has 108 divisors (see below), whose sum is σ = 62555220. Its totient is φ = 5644800.

The previous prime is 20513551. The next prime is 20513557. The reversal of 20513556 is 65531502.

It can be written as a sum of positive squares in 2 ways, for example, as 16941456 + 3572100 = 4116^2 + 1890^2 .

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20513551) by changing a digit.

It is a polite number, since it can be written in 35 ways as a sum of consecutive naturals, for example, 50956 + ... + 51356.

It is an arithmetic number, because the mean of its divisors is an integer number (579215).

Almost surely, 2^20513556 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 20513556, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (31277610).

20513556 is an abundant number, since it is smaller than the sum of its proper divisors (42041664).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

20513556 is a wasteful number, since it uses less digits than its factorization.

20513556 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 454 (or 442 counting only the distinct ones).

The product of its (nonzero) digits is 4500, while the sum is 27.

The square root of 20513556 is about 4529.1893314367. The cubic root of 20513556 is about 273.7454968922.

The spelling of 20513556 in words is "twenty million, five hundred thirteen thousand, five hundred fifty-six".