20636400 has 120 divisors (see below), whose sum is σ = 68500080. Its totient is φ = 5304320.

The previous prime is 20636389. The next prime is 20636401. The reversal of 20636400 is 463602.

It is a tau number, because it is divible by the number of its divisors (120).

It is a super-2 number, since 2×20636400² = 851722009920000, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20636401) 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 23 ways as a sum of consecutive naturals, for example, 34504 + ... + 35096.

It is an arithmetic number, because the mean of its divisors is an integer number (570834).

Almost surely, 2^20636400 is an apocalyptic number.

20636400 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 20636400, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (34250040).

20636400 is an abundant number, since it is smaller than the sum of its proper divisors (47863680).

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

20636400 is a wasteful number, since it uses less digits than its factorization.

20636400 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 643 (or 632 counting only the distinct ones).

The product of its (nonzero) digits is 864, while the sum is 21.

The square root of 20636400 is about 4542.7304564546. The cubic root of 20636400 is about 274.2908450181.

The spelling of 20636400 in words is "twenty million, six hundred thirty-six thousand, four hundred".