21368772 has 60 divisors (see below), whose sum is σ = 56501676. Its totient is φ = 7041600.

The previous prime is 21368761. The next prime is 21368777. The reversal of 21368772 is 27786312.

It can be written as a sum of positive squares in 2 ways, for example, as 13883076 + 7485696 = 3726^2 + 2736^2 .

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21368777) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 19 ways as a sum of consecutive naturals, for example, 32398 + ... + 33050.

Almost surely, 2^21368772 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 21368772, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (28250838).

21368772 is an abundant number, since it is smaller than the sum of its proper divisors (35132904).

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

21368772 is a wasteful number, since it uses less digits than its factorization.

21368772 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 770 (or 759 counting only the distinct ones).

The product of its digits is 28224, while the sum is 36.

The square root of 21368772 is about 4622.6369098167. The cubic root of 21368772 is about 277.4979985246.

The spelling of 21368772 in words is "twenty-one million, three hundred sixty-eight thousand, seven hundred seventy-two".