21525357 has 24 divisors (see below), whose sum is σ = 33678336. Its totient is φ = 12192768.

The previous prime is 21525353. The next prime is 21525359. The reversal of 21525357 is 75352512.

It is not a de Polignac number, because 21525357 - 2² = 21525353 is a prime.

It is a hoax number, since the sum of its digits (30) coincides with the sum of the digits of its distinct prime factors.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21525353) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 18093 + ... + 19245.

It is an arithmetic number, because the mean of its divisors is an integer number (1403264).

Almost surely, 2^21525357 is an apocalyptic number.

It is an amenable number.

21525357 is a deficient number, since it is larger than the sum of its proper divisors (12152979).

21525357 is a wasteful number, since it uses less digits than its factorization.

21525357 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1297 (or 1290 counting only the distinct ones).

The product of its digits is 10500, while the sum is 30.

The square root of 21525357 is about 4639.5427576433. The cubic root of 21525357 is about 278.1741615239.

Adding to 21525357 its reverse (75352512), we get a palindrome (96877869).

The spelling of 21525357 in words is "twenty-one million, five hundred twenty-five thousand, three hundred fifty-seven".