20812500 has 126 divisors (see below), whose sum is σ = 67538198. Its totient is φ = 5400000.

The previous prime is 20812483. The next prime is 20812511. The reversal of 20812500 is 521802.

It can be written as a sum of positive squares in 7 ways, for example, as 20034576 + 777924 = 4476^2 + 882^2 .

It is a Harshad number since it is a multiple of its sum of digits (18).

It is a congruent number.

It is an unprimeable number.

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 41 ways as a sum of consecutive naturals, for example, 562482 + ... + 562518.

Almost surely, 2^20812500 is an apocalyptic number.

20812500 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 20812500, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (33769099).

20812500 is an abundant number, since it is smaller than the sum of its proper divisors (46725698).

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

20812500 is an equidigital number, since it uses as much as digits as its factorization.

20812500 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 77 (or 47 counting only the distinct ones).

The product of its (nonzero) digits is 160, while the sum is 18.

The square root of 20812500 is about 4562.0718977237. The cubic root of 20812500 is about 275.0688532828.

It can be divided in two parts, 20812 and 500, that added together give a palindrome (21312).

The spelling of 20812500 in words is "twenty million, eight hundred twelve thousand, five hundred".