20405400 has 96 divisors (see below), whose sum is σ = 64281600. Its totient is φ = 5353600.

The previous prime is 20405387. The next prime is 20405443. The reversal of 20405400 is 450402.

It is a Harshad number since it is a multiple of its sum of digits (15).

It is a self number, because there is not a number n which added to its sum of digits gives 20405400.

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 23 ways as a sum of consecutive naturals, for example, 42361 + ... + 42839.

It is an arithmetic number, because the mean of its divisors is an integer number (669600).

Almost surely, 2^20405400 is an apocalyptic number.

20405400 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 20405400, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (32140800).

20405400 is an abundant number, since it is smaller than the sum of its proper divisors (43876200).

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

20405400 is a wasteful number, since it uses less digits than its factorization.

20405400 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 569 (or 560 counting only the distinct ones).

The product of its (nonzero) digits is 160, while the sum is 15.

The square root of 20405400 is about 4517.2336667478. The cubic root of 20405400 is about 273.2635488450.

Adding to 20405400 its reverse (450402), we get a palindrome (20855802).

The spelling of 20405400 in words is "twenty million, four hundred five thousand, four hundred".