21253100 has 54 divisors (see below), whose sum is σ = 50676444. Its totient is φ = 7672800.

The previous prime is 21253093. The next prime is 21253103. The reversal of 21253100 is 135212.

It is a happy number.

It is a super-2 number, since 2×21253100² = 903388519220000, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (21253103) by changing a digit.

It is a polite number, since it can be written in 17 ways as a sum of consecutive naturals, for example, 152831 + ... + 152969.

Almost surely, 2^21253100 is an apocalyptic number.

21253100 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 21253100, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (25338222).

21253100 is an abundant number, since it is smaller than the sum of its proper divisors (29423344).

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

21253100 is a wasteful number, since it uses less digits than its factorization.

21253100 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 303 (or 157 counting only the distinct ones).

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

The square root of 21253100 is about 4610.1084585940. The cubic root of 21253100 is about 276.9963811558.

Adding to 21253100 its reverse (135212), we get a palindrome (21388312).

It can be divided in two parts, 2125 and 3100, that added together give a palindrome (5225).

The spelling of 21253100 in words is "twenty-one million, two hundred fifty-three thousand, one hundred".