21643125 has 80 divisors (see below), whose sum is σ = 44085888. Its totient is φ = 9216000.

The previous prime is 21643117. The next prime is 21643129. The reversal of 21643125 is 52134612.

It is not a de Polignac number, because 21643125 - 2³ = 21643117 is a prime.

It is a super-3 number, since 3×21643125³ (a number of 23 digits) contains 333 as substring.

21643125 is a Rhonda number in base 10.

Its product of digits (1440) is a multiple of the sum of its prime factors (144).

It is a junction number, because it is equal to n+sod(n) for n = 21643095 and 21643104.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21643129) by changing a digit.

It is a polite number, since it can be written in 79 ways as a sum of consecutive naturals, for example, 223077 + ... + 223173.

Almost surely, 2^21643125 is an apocalyptic number.

21643125 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

It is an amenable number.

21643125 is an abundant number, since it is smaller than the sum of its proper divisors (22442763).

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

21643125 is an equidigital number, since it uses as much as digits as its factorization.

21643125 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 144 (or 129 counting only the distinct ones).

The product of its digits is 1440, while the sum is 24.

The square root of 21643125 is about 4652.2172133296. The cubic root of 21643125 is about 278.6805480279.

Adding to 21643125 its reverse (52134612), we get a palindrome (73777737).

It can be divided in two parts, 21 and 643125, that multiplied together give a square (13505625 = 3675²).

The spelling of 21643125 in words is "twenty-one million, six hundred forty-three thousand, one hundred twenty-five".