20516400 has 180 divisors, whose sum is σ = 73458840. Its totient is φ = 5299200.

The previous prime is 20516387. The next prime is 20516417. The reversal of 20516400 is 461502.

It is a happy number.

20516400 is a `hidden beast` number, since 20 + 5 + 1 + 640 + 0 = 666.

It is a tau number, because it is divible by the number of its divisors (180).

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 35 ways as a sum of consecutive naturals, for example, 147531 + ... + 147669.

Almost surely, 2^20516400 is an apocalyptic number.

20516400 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 20516400, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (36729420).

20516400 is an abundant number, since it is smaller than the sum of its proper divisors (52942440).

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

20516400 is a wasteful number, since it uses less digits than its factorization.

20516400 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 204 (or 190 counting only the distinct ones).

The product of its (nonzero) digits is 240, while the sum is 18.

The square root of 20516400 is about 4529.5032840257. The cubic root of 20516400 is about 273.7581470022.

Adding to 20516400 its reverse (461502), we get a palindrome (20977902).

The spelling of 20516400 in words is "twenty million, five hundred sixteen thousand, four hundred".