21229021 has 16 divisors (see below), whose sum is σ = 24006528. Its totient is φ = 18604800.

The previous prime is 21229001. The next prime is 21229031. The reversal of 21229021 is 12092212.

It is a cyclic number.

It is not a de Polignac number, because 21229021 - 2⁵ = 21228989 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21229021.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21229001) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 46225 + ... + 46681.

It is an arithmetic number, because the mean of its divisors is an integer number (1500408).

Almost surely, 2^21229021 is an apocalyptic number.

It is an amenable number.

21229021 is a deficient number, since it is larger than the sum of its proper divisors (2777507).

21229021 is a wasteful number, since it uses less digits than its factorization.

21229021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 612.

The product of its (nonzero) digits is 144, while the sum is 19.

The square root of 21229021 is about 4607.4961747136. The cubic root of 21229021 is about 276.8917326367.

The spelling of 21229021 in words is "twenty-one million, two hundred twenty-nine thousand, twenty-one".