21435021 has 24 divisors (see below), whose sum is σ = 32934720. Its totient is φ = 13395456.

The previous prime is 21435019. The next prime is 21435023. The reversal of 21435021 is 12053412.

It is an interprime number because it is at equal distance from previous prime (21435019) and next prime (21435023).

It is not a de Polignac number, because 21435021 - 2¹ = 21435019 is a prime.

It is a Curzon number.

It is a zygodrome in base 3.

It is a junction number, because it is equal to n+sod(n) for n = 21434985 and 21435003.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21435023) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 17005 + ... + 18221.

It is an arithmetic number, because the mean of its divisors is an integer number (1372280).

Almost surely, 2^21435021 is an apocalyptic number.

It is an amenable number.

21435021 is a deficient number, since it is larger than the sum of its proper divisors (11499699).

21435021 is a wasteful number, since it uses less digits than its factorization.

21435021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1345 (or 1342 counting only the distinct ones).

The product of its (nonzero) digits is 240, while the sum is 18.

The square root of 21435021 is about 4629.7970797865. The cubic root of 21435021 is about 277.7844757437.

Adding to 21435021 its reverse (12053412), we get a palindrome (33488433).

The spelling of 21435021 in words is "twenty-one million, four hundred thirty-five thousand, twenty-one".