21051522 has 32 divisors (see below), whose sum is σ = 47275200. Its totient is φ = 6943104.

The previous prime is 21051493. The next prime is 21051523. The reversal of 21051522 is 22515012.

It is a Harshad number since it is a multiple of its sum of digits (18).

It is a junction number, because it is equal to n+sod(n) for n = 21051495 and 21051504.

It is not an unprimeable number, because it can be changed into a prime (21051523) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 3229 + ... + 7247.

It is an arithmetic number, because the mean of its divisors is an integer number (1477350).

Almost surely, 2^21051522 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21051522, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (23637600).

21051522 is an abundant number, since it is smaller than the sum of its proper divisors (26223678).

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

21051522 is a wasteful number, since it uses less digits than its factorization.

21051522 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4127 (or 4121 counting only the distinct ones).

The product of its (nonzero) digits is 200, while the sum is 18.

The square root of 21051522 is about 4588.1937622555. The cubic root of 21051522 is about 276.1178608156.

Adding to 21051522 its reverse (22515012), we get a palindrome (43566534).

The spelling of 21051522 in words is "twenty-one million, fifty-one thousand, five hundred twenty-two".