20420400 has 480 divisors, whose sum is σ = 92994048. Its totient is φ = 3686400.

The previous prime is 20420377. The next prime is 20420443. The reversal of 20420400 is 402402.

It is a Harshad number since it is a multiple of its sum of digits (12).

It is a super Niven number, because it is divisible the sum of any subset of its (nonzero) digits.

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 95 ways as a sum of consecutive naturals, for example, 1201192 + ... + 1201208.

Almost surely, 2^20420400 is an apocalyptic number.

20420400 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 20420400, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (46497024).

20420400 is an abundant number, since it is smaller than the sum of its proper divisors (72573648).

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

20420400 is a wasteful number, since it uses less digits than its factorization.

20420400 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 69 (or 58 counting only the distinct ones).

The product of its (nonzero) digits is 64, while the sum is 12.

The square root of 20420400 is about 4518.8936699152. The cubic root of 20420400 is about 273.3304910802.

Adding to 20420400 its reverse (402402), we get a palindrome (20822802).

It can be divided in two parts, 204 and 20400, that multiplied together give a square (4161600 = 2040²).

The spelling of 20420400 in words is "twenty million, four hundred twenty thousand, four hundred".