20686400 has 84 divisors (see below), whose sum is σ = 58204608. Its totient is φ = 7088640.

The previous prime is 20686373. The next prime is 20686409. The reversal of 20686400 is 468602.

20686400 = T₅₁ + T₅₂ + ... + T₄₉₈.

It is a self number, because there is not a number n which added to its sum of digits gives 20686400.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20686409) 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, 10277 + ... + 12123.

It is an arithmetic number, because the mean of its divisors is an integer number (692912).

Almost surely, 2^20686400 is an apocalyptic number.

20686400 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 20686400, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (29102304).

20686400 is an abundant number, since it is smaller than the sum of its proper divisors (37518208).

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

20686400 is a wasteful number, since it uses less digits than its factorization.

20686400 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1876 (or 1861 counting only the distinct ones).

The product of its (nonzero) digits is 2304, while the sum is 26.

The square root of 20686400 is about 4548.2304251214. The cubic root of 20686400 is about 274.5121930698.

The spelling of 20686400 in words is "twenty million, six hundred eighty-six thousand, four hundred".