21021136 has 20 divisors (see below), whose sum is σ = 40817700. Its totient is φ = 10487552.

The previous prime is 21021127. The next prime is 21021157. The reversal of 21021136 is 63112012.

It can be written as a sum of positive squares in 2 ways, for example, as 10497600 + 10523536 = 3240^2 + 3244^2 .

It is a Harshad number since it is a multiple of its sum of digits (16).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 7950 + ... + 10258.

It is an arithmetic number, because the mean of its divisors is an integer number (2040885).

Almost surely, 2^21021136 is an apocalyptic number.

It is an amenable number.

21021136 is a deficient number, since it is larger than the sum of its proper divisors (19796564).

21021136 is a wasteful number, since it uses less digits than its factorization.

21021136 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2886 (or 2880 counting only the distinct ones).

The product of its (nonzero) digits is 72, while the sum is 16.

The square root of 21021136 is about 4584.8812416463. The cubic root of 21021136 is about 275.9849463189.

Adding to 21021136 its reverse (63112012), we get a palindrome (84133148).

The spelling of 21021136 in words is "twenty-one million, twenty-one thousand, one hundred thirty-six".