21128161600 has 504 divisors, whose sum is σ = 66554323584. Its totient is φ = 6428160000.

The previous prime is 21128161573. The next prime is 21128161601. The reversal of 21128161600 is 616182112.

It is a Harshad number since it is a multiple of its sum of digits (28).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21128161601) by changing a digit.

It is a polite number, since it can be written in 71 ways as a sum of consecutive naturals, for example, 139921525 + ... + 139921675.

Almost surely, 2^21128161600 is an apocalyptic number.

21128161600 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 21128161600, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (33277161792).

21128161600 is an abundant number, since it is smaller than the sum of its proper divisors (45426161984).

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

21128161600 is a wasteful number, since it uses less digits than its factorization.

21128161600 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 255 (or 209 counting only the distinct ones).

The product of its (nonzero) digits is 1152, while the sum is 28.

The spelling of 21128161600 in words is "twenty-one billion, one hundred twenty-eight million, one hundred sixty-one thousand, six hundred".