21128000220 has 72 divisors (see below), whose sum is σ = 64102496640. Its totient is φ = 5632882560.

The previous prime is 21128000219. The next prime is 21128000227. The reversal of 21128000220 is 2200082112.

It is a happy number.

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

It is a junction number, because it is equal to n+sod(n) for n = 21128000193 and 21128000202.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21128000227) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 1032246 + ... + 1052514.

Almost surely, 2^21128000220 is an apocalyptic number.

21128000220 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21128000220 is an abundant number, since it is smaller than the sum of its proper divisors (42974496420).

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

21128000220 is a wasteful number, since it uses less digits than its factorization.

21128000220 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 26075 (or 26070 counting only the distinct ones).

The product of its (nonzero) digits is 128, while the sum is 18.

Adding to 21128000220 its reverse (2200082112), we get a palindrome (23328082332).

The spelling of 21128000220 in words is "twenty-one billion, one hundred twenty-eight million, two hundred twenty", and thus it is an aban number.