21331325 has 12 divisors (see below), whose sum is σ = 26593908. Its totient is φ = 16972800.

The previous prime is 21331313. The next prime is 21331333. The reversal of 21331325 is 52313312.

It can be written as a sum of positive squares in 6 ways, for example, as 198916 + 21132409 = 446^2 + 4597^2 .

It is not a de Polignac number, because 21331325 - 2⁴ = 21331309 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a junction number, because it is equal to n+sod(n) for n = 21331297 and 21331306.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 2615 + ... + 7035.

It is an arithmetic number, because the mean of its divisors is an integer number (2216159).

Almost surely, 2^21331325 is an apocalyptic number.

21331325 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

It is an amenable number.

21331325 is a deficient number, since it is larger than the sum of its proper divisors (5262583).

21331325 is a wasteful number, since it uses less digits than its factorization.

21331325 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4624 (or 4619 counting only the distinct ones).

The product of its digits is 540, while the sum is 20.

The square root of 21331325 is about 4618.5847399393. The cubic root of 21331325 is about 277.3358063386.

Adding to 21331325 its reverse (52313312), we get a palindrome (73644637).

The spelling of 21331325 in words is "twenty-one million, three hundred thirty-one thousand, three hundred twenty-five".