21051320 has 16 divisors (see below), whose sum is σ = 47365560. Its totient is φ = 8420512.

The previous prime is 21051311. The next prime is 21051323. The reversal of 21051320 is 2315012.

It is a happy number.

It is a junction number, because it is equal to n+sod(n) for n = 21051295 and 21051304.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21051323) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 263102 + ... + 263181.

Almost surely, 2^21051320 is an apocalyptic number.

21051320 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21051320 is an abundant number, since it is smaller than the sum of its proper divisors (26314240).

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

21051320 is a wasteful number, since it uses less digits than its factorization.

21051320 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 526294 (or 526290 counting only the distinct ones).

The product of its (nonzero) digits is 60, while the sum is 14.

The square root of 21051320 is about 4588.1717491829. The cubic root of 21051320 is about 276.1169776493.

Adding to 21051320 its reverse (2315012), we get a palindrome (23366332).

The spelling of 21051320 in words is "twenty-one million, fifty-one thousand, three hundred twenty".