21403325 has 6 divisors (see below), whose sum is σ = 26540154. Its totient is φ = 17122640.

The previous prime is 21403313. The next prime is 21403337. The reversal of 21403325 is 52330412.

It is a happy number.

It is an interprime number because it is at equal distance from previous prime (21403313) and next prime (21403337).

It can be written as a sum of positive squares in 3 ways, for example, as 3247204 + 18156121 = 1802^2 + 4261^2 .

It is not a de Polignac number, because 21403325 - 2¹² = 21399229 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 = 21403297 and 21403306.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 428042 + ... + 428091.

It is an arithmetic number, because the mean of its divisors is an integer number (4423359).

Almost surely, 2^21403325 is an apocalyptic number.

21403325 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

It is an amenable number.

21403325 is a deficient number, since it is larger than the sum of its proper divisors (5136829).

21403325 is an equidigital number, since it uses as much as digits as its factorization.

21403325 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 856143 (or 856138 counting only the distinct ones).

The product of its (nonzero) digits is 720, while the sum is 20.

The square root of 21403325 is about 4626.3727692437. The cubic root of 21403325 is about 277.6474880833.

Adding to 21403325 its reverse (52330412), we get a palindrome (73733737).

The spelling of 21403325 in words is "twenty-one million, four hundred three thousand, three hundred twenty-five".