21009153 has 16 divisors (see below), whose sum is σ = 30647232. Its totient is φ = 12696000.

The previous prime is 21009151. The next prime is 21009167. The reversal of 21009153 is 35190012.

It is not a de Polignac number, because 21009153 - 2¹ = 21009151 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21009151) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 14523 + ... + 15903.

It is an arithmetic number, because the mean of its divisors is an integer number (1915452).

Almost surely, 2^21009153 is an apocalyptic number.

It is an amenable number.

21009153 is a deficient number, since it is larger than the sum of its proper divisors (9638079).

21009153 is a wasteful number, since it uses less digits than its factorization.

21009153 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1856.

The product of its (nonzero) digits is 270, while the sum is 21.

The square root of 21009153 is about 4583.5742603344. The cubic root of 21009153 is about 275.9324950430.

Adding to 21009153 its reverse (35190012), we get a palindrome (56199165).

The spelling of 21009153 in words is "twenty-one million, nine thousand, one hundred fifty-three".