21225546 has 48 divisors (see below), whose sum is σ = 49364640. Its totient is φ = 6570720.

The previous prime is 21225541. The next prime is 21225551. The reversal of 21225546 is 64552212.

It is an interprime number because it is at equal distance from previous prime (21225541) and next prime (21225551).

It is not an unprimeable number, because it can be changed into a prime (21225541) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 17541 + ... + 18711.

It is an arithmetic number, because the mean of its divisors is an integer number (1028430).

Almost surely, 2^21225546 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21225546, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (24682320).

21225546 is an abundant number, since it is smaller than the sum of its proper divisors (28139094).

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

21225546 is a wasteful number, since it uses less digits than its factorization.

21225546 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1251 (or 1248 counting only the distinct ones).

The product of its digits is 4800, while the sum is 27.

The square root of 21225546 is about 4607.1190564169. The cubic root of 21225546 is about 276.8766235826.

Adding to 21225546 its reverse (64552212), we get a palindrome (85777758).

The spelling of 21225546 in words is "twenty-one million, two hundred twenty-five thousand, five hundred forty-six".