20390400 has 240 divisors, whose sum is σ = 76111200. Its totient is φ = 5345280.

The previous prime is 20390399. The next prime is 20390411. The reversal of 20390400 is 409302.

20390400 is nontrivially palindromic in base 14.

It is a tau number, because it is divible by the number of its divisors (240).

It is a Harshad number since it is a multiple of its sum of digits (18).

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 345571 + ... + 345629.

It is an arithmetic number, because the mean of its divisors is an integer number (317130).

Almost surely, 2^20390400 is an apocalyptic number.

20390400 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 20390400, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (38055600).

20390400 is an abundant number, since it is smaller than the sum of its proper divisors (55720800).

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

20390400 is an equidigital number, since it uses as much as digits as its factorization.

20390400 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 96 (or 69 counting only the distinct ones).

The product of its (nonzero) digits is 216, while the sum is 18.

The square root of 20390400 is about 4515.5730533344. The cubic root of 20390400 is about 273.1965737955.

Adding to 20390400 its reverse (409302), we get a palindrome (20799702).

The spelling of 20390400 in words is "twenty million, three hundred ninety thousand, four hundred".