21254420 has 48 divisors (see below), whose sum is σ = 51565248. Its totient is φ = 7272960.

The previous prime is 21254417. The next prime is 21254447. The reversal of 21254420 is 2445212.

It is a happy number.

It is a Harshad number since it is a multiple of its sum of digits (20).

It is a junction number, because it is equal to n+sod(n) for n = 21254392 and 21254401.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 899 + ... + 6581.

It is an arithmetic number, because the mean of its divisors is an integer number (1074276).

Almost surely, 2^21254420 is an apocalyptic number.

21254420 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 21254420, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (25782624).

21254420 is an abundant number, since it is smaller than the sum of its proper divisors (30310828).

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

21254420 is a wasteful number, since it uses less digits than its factorization.

21254420 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5720 (or 5718 counting only the distinct ones).

The product of its (nonzero) digits is 640, while the sum is 20.

The square root of 21254420 is about 4610.2516200312. The cubic root of 21254420 is about 277.0021156550.

Adding to 21254420 its reverse (2445212), we get a palindrome (23699632).

The spelling of 21254420 in words is "twenty-one million, two hundred fifty-four thousand, four hundred twenty".