20778400 has 72 divisors (see below), whose sum is σ = 53434080. Its totient is φ = 7868160.

The previous prime is 20778391. The next prime is 20778449. The reversal of 20778400 is 487702.

It is a congruent number.

It is an unprimeable number.

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, 14517 + ... + 15883.

It is an arithmetic number, because the mean of its divisors is an integer number (742140).

Almost surely, 2^20778400 is an apocalyptic number.

20778400 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 20778400, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (26717040).

20778400 is an abundant number, since it is smaller than the sum of its proper divisors (32655680).

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

20778400 is a wasteful number, since it uses less digits than its factorization.

20778400 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1406 (or 1393 counting only the distinct ones).

The product of its (nonzero) digits is 3136, while the sum is 28.

The square root of 20778400 is about 4558.3330286411. Note that the first 3 decimals coincide. The cubic root of 20778400 is about 274.9185433676.

The spelling of 20778400 in words is "twenty million, seven hundred seventy-eight thousand, four hundred".