21421980 has 72 divisors (see below), whose sum is σ = 66079104. Its totient is φ = 5616000.

The previous prime is 21421943. The next prime is 21421997. The reversal of 21421980 is 8912412.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 10005 + ... + 11955.

Almost surely, 2^21421980 is an apocalyptic number.

21421980 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 21421980, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (33039552).

21421980 is an abundant number, since it is smaller than the sum of its proper divisors (44657124).

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

21421980 is a wasteful number, since it uses less digits than its factorization.

21421980 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2027 (or 2022 counting only the distinct ones).

The product of its (nonzero) digits is 1152, while the sum is 27.

The square root of 21421980 is about 4628.3884884482. The cubic root of 21421980 is about 277.7281299120.

The spelling of 21421980 in words is "twenty-one million, four hundred twenty-one thousand, nine hundred eighty".