21189980 has 24 divisors (see below), whose sum is σ = 50856288. Its totient is φ = 7265088.

The previous prime is 21189977. The next prime is 21190003. The reversal of 21189980 is 8998112.

It is a Smith number, since the sum of its digits (38) coincides with the sum of the digits of its prime factors.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 75539 + ... + 75818.

It is an arithmetic number, because the mean of its divisors is an integer number (2119012).

Almost surely, 2^21189980 is an apocalyptic number.

21189980 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21189980 is an abundant number, since it is smaller than the sum of its proper divisors (29666308).

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

21189980 is a wasteful number, since it uses less digits than its factorization.

21189980 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 151373 (or 151371 counting only the distinct ones).

The product of its (nonzero) digits is 10368, while the sum is 38.

The square root of 21189980 is about 4603.2575422194. The cubic root of 21189980 is about 276.7218902361.

The spelling of 21189980 in words is "twenty-one million, one hundred eighty-nine thousand, nine hundred eighty".