21525570 has 96 divisors (see below), whose sum is σ = 64696320. Its totient is φ = 4907520.

The previous prime is 21525551. The next prime is 21525571. The reversal of 21525570 is 7552512.

It is a happy number.

It is not an unprimeable number, because it can be changed into a prime (21525571) by changing a digit.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 16191 + ... + 17469.

It is an arithmetic number, because the mean of its divisors is an integer number (673920).

Almost surely, 2^21525570 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21525570, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (32348160).

21525570 is an abundant number, since it is smaller than the sum of its proper divisors (43170750).

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

21525570 is a wasteful number, since it uses less digits than its factorization.

21525570 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1320 (or 1317 counting only the distinct ones).

The product of its (nonzero) digits is 3500, while the sum is 27.

The square root of 21525570 is about 4639.5657124347. The cubic root of 21525570 is about 278.1750790604.

The spelling of 21525570 in words is "twenty-one million, five hundred twenty-five thousand, five hundred seventy".