21816325 has 12 divisors (see below), whose sum is σ = 27113220. Its totient is φ = 17413760.

The previous prime is 21816317. The next prime is 21816331. The reversal of 21816325 is 52361812.

It can be written as a sum of positive squares in 6 ways, for example, as 3006756 + 18809569 = 1734^2 + 4337^2 .

It is not a de Polignac number, because 21816325 - 2³ = 21816317 is a prime.

It is an alternating number because its digits alternate between even and odd.

It is a junction number, because it is equal to n+sod(n) for n = 21816293 and 21816302.

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, 16281 + ... + 17569.

It is an arithmetic number, because the mean of its divisors is an integer number (2259435).

Almost surely, 2^21816325 is an apocalyptic number.

21816325 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

It is an amenable number.

21816325 is a deficient number, since it is larger than the sum of its proper divisors (5296895).

21816325 is a wasteful number, since it uses less digits than its factorization.

21816325 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1976 (or 1971 counting only the distinct ones).

The product of its digits is 2880, while the sum is 28.

The square root of 21816325 is about 4670.7949002284. The cubic root of 21816325 is about 279.4219580008.

The spelling of 21816325 in words is "twenty-one million, eight hundred sixteen thousand, three hundred twenty-five".