21253120 has 88 divisors (see below), whose sum is σ = 58364064. Its totient is φ = 7274496.

The previous prime is 21253117. The next prime is 21253121. The reversal of 21253120 is 2135212.

It is a Harshad number since it is a multiple of its sum of digits (16).

It is a junction number, because it is equal to n+sod(n) for n = 21253094 and 21253103.

It is not an unprimeable number, because it can be changed into a prime (21253121) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 35544 + ... + 36136.

It is an arithmetic number, because the mean of its divisors is an integer number (663228).

Almost surely, 2^21253120 is an apocalyptic number.

21253120 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21253120, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (29182032).

21253120 is an abundant number, since it is smaller than the sum of its proper divisors (37110944).

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

21253120 is an equidigital number, since it uses as much as digits as its factorization.

21253120 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 625 (or 607 counting only the distinct ones).

The product of its (nonzero) digits is 120, while the sum is 16.

The square root of 21253120 is about 4610.1106277399. The cubic root of 21253120 is about 276.9964680440.

Adding to 21253120 its reverse (2135212), we get a palindrome (23388332).

The spelling of 21253120 in words is "twenty-one million, two hundred fifty-three thousand, one hundred twenty".