21251542 has 16 divisors (see below), whose sum is σ = 35258832. Its totient is φ = 9542880.

The previous prime is 21251539. The next prime is 21251543. The reversal of 21251542 is 24515212.

It is a super-3 number, since 3×21251542³ (a number of 23 digits) contains 333 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21251543) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 10084 + ... + 12007.

It is an arithmetic number, because the mean of its divisors is an integer number (2203677).

Almost surely, 2^21251542 is an apocalyptic number.

21251542 is a deficient number, since it is larger than the sum of its proper divisors (14007290).

21251542 is a wasteful number, since it uses less digits than its factorization.

21251542 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 22143.

The product of its digits is 800, while the sum is 22.

The square root of 21251542 is about 4609.9394789954. The cubic root of 21251542 is about 276.9896124035.

Adding to 21251542 its reverse (24515212), we get a palindrome (45766754).

The spelling of 21251542 in words is "twenty-one million, two hundred fifty-one thousand, five hundred forty-two".