21050736 has 160 divisors (see below), whose sum is σ = 67043328. Its totient is φ = 5564160.

The previous prime is 21050707. The next prime is 21050737. The reversal of 21050736 is 63705012.

21050736 = 809² + 810² + ... + 839².

It is a super-2 number, since 2×21050736² = 886266972283392, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (24).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21050737) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 447865 + ... + 447911.

Almost surely, 2^21050736 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 21050736, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (33521664).

21050736 is an abundant number, since it is smaller than the sum of its proper divisors (45992592).

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

21050736 is a wasteful number, since it uses less digits than its factorization.

21050736 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 139 (or 133 counting only the distinct ones).

The product of its (nonzero) digits is 1260, while the sum is 24.

The square root of 21050736 is about 4588.1081068344. The cubic root of 21050736 is about 276.1144243050.

Adding to 21050736 its reverse (63705012), we get a palindrome (84755748).

The spelling of 21050736 in words is "twenty-one million, fifty thousand, seven hundred thirty-six".