21725420 has 48 divisors (see below), whose sum is σ = 47889408. Its totient is φ = 8268480.

The previous prime is 21725419. The next prime is 21725441. The reversal of 21725420 is 2452712.

It is a happy number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 41279 + ... + 41801.

It is an arithmetic number, because the mean of its divisors is an integer number (997696).

Almost surely, 2^21725420 is an apocalyptic number.

21725420 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 21725420, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (23944704).

21725420 is an abundant number, since it is smaller than the sum of its proper divisors (26163988).

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

21725420 is a wasteful number, since it uses less digits than its factorization.

21725420 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 630 (or 628 counting only the distinct ones).

The product of its (nonzero) digits is 1120, while the sum is 23.

The square root of 21725420 is about 4661.0535289782. The cubic root of 21725420 is about 279.0333160799.

The spelling of 21725420 in words is "twenty-one million, seven hundred twenty-five thousand, four hundred twenty".