21213045 has 24 divisors (see below), whose sum is σ = 42022656. Its totient is φ = 9697248.

The previous prime is 21213041. The next prime is 21213047. The reversal of 21213045 is 54031212.

It is not a de Polignac number, because 21213045 - 2² = 21213041 is a prime.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21213041) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 33357 + ... + 33986.

It is an arithmetic number, because the mean of its divisors is an integer number (1750944).

Almost surely, 2^21213045 is an apocalyptic number.

It is an amenable number.

21213045 is a deficient number, since it is larger than the sum of its proper divisors (20809611).

21213045 is a wasteful number, since it uses less digits than its factorization.

21213045 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 67361 (or 67358 counting only the distinct ones).

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

The square root of 21213045 is about 4605.7621519136. The cubic root of 21213045 is about 276.8222564786.

Adding to 21213045 its reverse (54031212), we get a palindrome (75244257).

The spelling of 21213045 in words is "twenty-one million, two hundred thirteen thousand, forty-five".