21213136 has 40 divisors (see below), whose sum is σ = 48250880. Its totient is φ = 8843904.

The previous prime is 21213119. The next prime is 21213149. The reversal of 21213136 is 63131212.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1585 + ... + 6703.

It is an arithmetic number, because the mean of its divisors is an integer number (1206272).

Almost surely, 2^21213136 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21213136, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (24125440).

21213136 is an abundant number, since it is smaller than the sum of its proper divisors (27037744).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21213136 is a wasteful number, since it uses less digits than its factorization.

21213136 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5171 (or 5165 counting only the distinct ones).

The product of its digits is 216, while the sum is 19.

The square root of 21213136 is about 4605.7720308326. The cubic root of 21213136 is about 276.8226523166.

Adding to 21213136 its reverse (63131212), we get a palindrome (84344348).

The spelling of 21213136 in words is "twenty-one million, two hundred thirteen thousand, one hundred thirty-six".