21252550 has 48 divisors (see below), whose sum is σ = 45680112. Its totient is φ = 7270400.

The previous prime is 21252547. The next prime is 21252551. The reversal of 21252550 is 5525212.

It is a Harshad number since it is a multiple of its sum of digits (22).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21252551) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 8214 + ... + 10486.

It is an arithmetic number, because the mean of its divisors is an integer number (951669).

Almost surely, 2^21252550 is an apocalyptic number.

21252550 is an abundant number, since it is smaller than the sum of its proper divisors (24427562).

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

21252550 is a wasteful number, since it uses less digits than its factorization.

21252550 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2313 (or 2308 counting only the distinct ones).

The product of its (nonzero) digits is 1000, while the sum is 22.

The square root of 21252550 is about 4610.0488066831. The cubic root of 21252550 is about 276.9939917111.

Adding to 21252550 its reverse (5525212), we get a palindrome (26777762).

The spelling of 21252550 in words is "twenty-one million, two hundred fifty-two thousand, five hundred fifty".