2121638400 has 480 divisors, whose sum is σ = 8910084480. Its totient is φ = 484392960.

The previous prime is 2121638399. The next prime is 2121638411. The reversal of 2121638400 is 48361212.

2121638400 is a `hidden beast` number, since 2 + 1 + 21 + 638 + 4 + 0 + 0 = 666.

It is a tau number, because it is divible by the number of its divisors (480).

It is a super-3 number, since 3×2121638400³ (a number of 29 digits) contains 333 as substring.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is an unprimeable number.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 2418762 + ... + 2419638.

It is an arithmetic number, because the mean of its divisors is an integer number (18562676).

Almost surely, 2^2121638400 is an apocalyptic number.

2121638400 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 2121638400, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (4455042240).

2121638400 is an abundant number, since it is smaller than the sum of its proper divisors (6788446080).

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

2121638400 is an equidigital number, since it uses as much as digits as its factorization.

2121638400 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 921 (or 894 counting only the distinct ones).

The product of its (nonzero) digits is 2304, while the sum is 27.

The square root of 2121638400 is about 46061.2461837497. The cubic root of 2121638400 is about 1284.9625065393.

Adding to 2121638400 its reverse (48361212), we get a palindrome (2169999612).

The spelling of 2121638400 in words is "two billion, one hundred twenty-one million, six hundred thirty-eight thousand, four hundred".