21163521 has 8 divisors (see below), whose sum is σ = 29877984. Its totient is φ = 13279040.

The previous prime is 21163507. The next prime is 21163531. The reversal of 21163521 is 12536112.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 21163521 - 2²² = 16969217 is a prime.

It is a super-2 number, since 2×21163521² = 895789242234882, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (21163531) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 207435 + ... + 207536.

It is an arithmetic number, because the mean of its divisors is an integer number (3734748).

Almost surely, 2^21163521 is an apocalyptic number.

It is an amenable number.

21163521 is a deficient number, since it is larger than the sum of its proper divisors (8714463).

21163521 is a wasteful number, since it uses less digits than its factorization.

21163521 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 414991.

The product of its digits is 360, while the sum is 21.

The square root of 21163521 is about 4600.3827014717. The cubic root of 21163521 is about 276.6066654290.

Adding to 21163521 its reverse (12536112), we get a palindrome (33699633).

The spelling of 21163521 in words is "twenty-one million, one hundred sixty-three thousand, five hundred twenty-one".