21251420 has 24 divisors (see below), whose sum is σ = 45133200. Its totient is φ = 8404352.

The previous prime is 21251413. The next prime is 21251441. The reversal of 21251420 is 2415212.

It is a plaindrome in base 16.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 4190 + ... + 7749.

It is an arithmetic number, because the mean of its divisors is an integer number (1880550).

Almost surely, 2^21251420 is an apocalyptic number.

21251420 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21251420 is an abundant number, since it is smaller than the sum of its proper divisors (23881780).

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

21251420 is a wasteful number, since it uses less digits than its factorization.

21251420 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 12037 (or 12035 counting only the distinct ones).

The product of its (nonzero) digits is 160, while the sum is 17.

The square root of 21251420 is about 4609.9262466985. The cubic root of 21251420 is about 276.9890823589.

Adding to 21251420 its reverse (2415212), we get a palindrome (23666632).

The spelling of 21251420 in words is "twenty-one million, two hundred fifty-one thousand, four hundred twenty".