21441420 has 432 divisors, whose sum is σ = 94112928. Its totient is φ = 3870720.

The previous prime is 21441383. The next prime is 21441421. The reversal of 21441420 is 2414412.

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 = 21441393 and 21441402.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21441421) by changing a digit.

It is a polite number, since it can be written in 143 ways as a sum of consecutive naturals, for example, 1261252 + ... + 1261268.

It is an arithmetic number, because the mean of its divisors is an integer number (217854).

Almost surely, 2^21441420 is an apocalyptic number.

21441420 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 21441420, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (47056464).

21441420 is an abundant number, since it is smaller than the sum of its proper divisors (72671508).

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

21441420 is a wasteful number, since it uses less digits than its factorization.

21441420 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 70 (or 58 counting only the distinct ones).

The product of its (nonzero) digits is 256, while the sum is 18.

The square root of 21441420 is about 4630.4880952228. The cubic root of 21441420 is about 277.8121153404.

Adding to 21441420 its reverse (2414412), we get a palindrome (23855832).

The spelling of 21441420 in words is "twenty-one million, four hundred forty-one thousand, four hundred twenty".