21128180 has 24 divisors (see below), whose sum is σ = 44997120. Its totient is φ = 8331680.

The previous prime is 21128167. The next prime is 21128183. The reversal of 21128180 is 8182112.

It is a happy number.

It is a super-2 number, since 2×21128180² = 892799980224800, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21128183) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 6020 + ... + 8859.

It is an arithmetic number, because the mean of its divisors is an integer number (1874880).

Almost surely, 2^21128180 is an apocalyptic number.

21128180 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21128180 is an abundant number, since it is smaller than the sum of its proper divisors (23868940).

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

21128180 is a wasteful number, since it uses less digits than its factorization.

21128180 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 14959 (or 14957 counting only the distinct ones).

The product of its (nonzero) digits is 256, while the sum is 23.

The square root of 21128180 is about 4596.5400030893. The cubic root of 21128180 is about 276.4526109970.

The spelling of 21128180 in words is "twenty-one million, one hundred twenty-eight thousand, one hundred eighty".