21621325 has 12 divisors (see below), whose sum is σ = 29248128. Its totient is φ = 15724400.

The previous prime is 21621293. The next prime is 21621329. The reversal of 21621325 is 52312612.

It is not a de Polignac number, because 21621325 - 2⁵ = 21621293 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21621296 and 21621305.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21621329) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 39037 + ... + 39586.

It is an arithmetic number, because the mean of its divisors is an integer number (2437344).

Almost surely, 2^21621325 is an apocalyptic number.

21621325 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

It is an amenable number.

21621325 is a deficient number, since it is larger than the sum of its proper divisors (7626803).

21621325 is a wasteful number, since it uses less digits than its factorization.

21621325 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 78644 (or 78639 counting only the distinct ones).

The product of its digits is 720, while the sum is 22.

The square root of 21621325 is about 4649.8736541975. The cubic root of 21621325 is about 278.5869497629.

Adding to 21621325 its reverse (52312612), we get a palindrome (73933937).

The spelling of 21621325 in words is "twenty-one million, six hundred twenty-one thousand, three hundred twenty-five".