21522240 has 224 divisors, whose sum is σ = 79004160. Its totient is φ = 5511168.

The previous prime is 21522223. The next prime is 21522251. The reversal of 21522240 is 4222512.

It is a Harshad number since it is a multiple of its sum of digits (18).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 406054 + ... + 406106.

Almost surely, 2^21522240 is an apocalyptic number.

21522240 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 21522240, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (39502080).

21522240 is an abundant number, since it is smaller than the sum of its proper divisors (57481920).

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

21522240 is a wasteful number, since it uses less digits than its factorization.

21522240 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 126 (or 110 counting only the distinct ones).

The product of its (nonzero) digits is 320, while the sum is 18.

The square root of 21522240 is about 4639.2068287586. The cubic root of 21522240 is about 278.1607337835.

Adding to 21522240 its reverse (4222512), we get a palindrome (25744752).

The spelling of 21522240 in words is "twenty-one million, five hundred twenty-two thousand, two hundred forty".