21021129 has 12 divisors (see below), whose sum is σ = 32150196. Its totient is φ = 13189632.

The previous prime is 21021127. The next prime is 21021157. The reversal of 21021129 is 92112012.

It can be written as a sum of positive squares in 2 ways, for example, as 18045504 + 2975625 = 4248^2 + 1725^2 .

It is not a de Polignac number, because 21021129 - 2¹ = 21021127 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21021127) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 68544 + ... + 68849.

It is an arithmetic number, because the mean of its divisors is an integer number (2679183).

Almost surely, 2^21021129 is an apocalyptic number.

It is an amenable number.

21021129 is a deficient number, since it is larger than the sum of its proper divisors (11129067).

21021129 is a wasteful number, since it uses less digits than its factorization.

21021129 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 137416 (or 137413 counting only the distinct ones).

The product of its (nonzero) digits is 72, while the sum is 18.

The square root of 21021129 is about 4584.8804782677. The cubic root of 21021129 is about 275.9849156847.

The spelling of 21021129 in words is "twenty-one million, twenty-one thousand, one hundred twenty-nine".