21159521 has 8 divisors (see below), whose sum is σ = 22344000. Its totient is φ = 19982160.

The previous prime is 21159499. The next prime is 21159527. The reversal of 21159521 is 12595112.

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

It is a cyclic number.

It is not a de Polignac number, because 21159521 - 2¹⁴ = 21143137 is a prime.

It is a super-3 number, since 3×21159521³ (a number of 23 digits) contains 333 as substring.

It is not an unprimeable number, because it can be changed into a prime (21159527) 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, 5036 + ... + 8226.

It is an arithmetic number, because the mean of its divisors is an integer number (2793000).

Almost surely, 2^21159521 is an apocalyptic number.

It is an amenable number.

21159521 is a deficient number, since it is larger than the sum of its proper divisors (1184479).

21159521 is a wasteful number, since it uses less digits than its factorization.

21159521 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3559.

The product of its digits is 900, while the sum is 26.

The square root of 21159521 is about 4599.9479344880. The cubic root of 21159521 is about 276.5892376992.

The spelling of 21159521 in words is "twenty-one million, one hundred fifty-nine thousand, five hundred twenty-one".