21253522 has 4 divisors (see below), whose sum is σ = 31880286. Its totient is φ = 10626760.

The previous prime is 21253513. The next prime is 21253523. The reversal of 21253522 is 22535212.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in only one way, i.e., 20349121 + 904401 = 4511^2 + 951^2 .

It is a junction number, because it is equal to n+sod(n) for n = 21253493 and 21253502.

It is not an unprimeable number, because it can be changed into a prime (21253523) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5313379 + ... + 5313382.

Almost surely, 2^21253522 is an apocalyptic number.

21253522 is a deficient number, since it is larger than the sum of its proper divisors (10626764).

21253522 is a wasteful number, since it uses less digits than its factorization.

21253522 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10626763.

The product of its digits is 1200, while the sum is 22.

The square root of 21253522 is about 4610.1542273551. The cubic root of 21253522 is about 276.9982144837.

Adding to 21253522 its reverse (22535212), we get a palindrome (43788734).

The spelling of 21253522 in words is "twenty-one million, two hundred fifty-three thousand, five hundred twenty-two".