1638400000 has 120 divisors (see below), whose sum is σ = 4095733950. Its totient is φ = 655360000.

The previous prime is 1638399989. The next prime is 1638400013. The reversal of 1638400000 is 48361.

It is a powerful number, because all its prime factors have an exponent greater than 1 and also an Achilles number because it is not a perfect power.

It can be written as a sum of positive squares in 3 ways, for example, as 2359296 + 1636040704 = 1536^2 + 40448^2 .

It is a super-3 number, since 3×1638400000³ (a number of 29 digits) contains 333 as substring.

It is an unprimeable number.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 327679998 + ... + 327680002.

Almost surely, 2^1638400000 is an apocalyptic number.

1638400000 is a gapful number since it is divisible by the number (10) 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 1638400000, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (2047866975).

1638400000 is an abundant number, since it is smaller than the sum of its proper divisors (2457333950).

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

1638400000 is an frugal number, since it uses more digits than its factorization.

1638400000 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 63 (or 7 counting only the distinct ones).

The product of its (nonzero) digits is 576, while the sum is 22.

The square root of 1638400000 is about 40477.1540501553. The cubic root of 1638400000 is about 1178.8900795649.

Adding to 1638400000 its reverse (48361), we get a palindrome (1638448361).

The spelling of 1638400000 in words is "one billion, six hundred thirty-eight million, four hundred thousand".