21051936 has 72 divisors (see below), whose sum is σ = 60815664. Its totient is φ = 6906240.

The previous prime is 21051913. The next prime is 21051949. The reversal of 21051936 is 63915012.

It is a tau number, because it is divible by the number of its divisors (72).

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 18751 + ... + 19841.

It is an arithmetic number, because the mean of its divisors is an integer number (844662).

Almost surely, 2^21051936 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 21051936, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (30407832).

21051936 is an abundant number, since it is smaller than the sum of its proper divisors (39763728).

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

21051936 is a wasteful number, since it uses less digits than its factorization.

21051936 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1174 (or 1163 counting only the distinct ones).

The product of its (nonzero) digits is 1620, while the sum is 27.

The square root of 21051936 is about 4588.2388778267. The cubic root of 21051936 is about 276.1196708517.

Subtracting from 21051936 its product of nonzero digits (1620), we obtain a triangular number (21050316 = T₆₄₈₈).

Adding to 21051936 its reverse (63915012), we get a palindrome (84966948).

The spelling of 21051936 in words is "twenty-one million, fifty-one thousand, nine hundred thirty-six".