216638825 has 24 divisors (see below), whose sum is σ = 294778008. Its totient is φ = 156948480.

The previous prime is 216638791. The next prime is 216638827. The reversal of 216638825 is 528836612.

It can be written as a sum of positive squares in 12 ways, for example, as 27741289 + 188897536 = 5267^2 + 13744^2 .

It is not a de Polignac number, because 216638825 - 2¹⁸ = 216376681 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (216638827) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 10937 + ... + 23513.

It is an arithmetic number, because the mean of its divisors is an integer number (12282417).

Almost surely, 2^216638825 is an apocalyptic number.

216638825 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

It is an amenable number.

216638825 is a deficient number, since it is larger than the sum of its proper divisors (78139183).

216638825 is a wasteful number, since it uses less digits than its factorization.

216638825 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 12653 (or 12648 counting only the distinct ones).

The product of its digits is 138240, while the sum is 41.

The square root of 216638825 is about 14718.6556791033. The cubic root of 216638825 is about 600.5909224563.

The spelling of 216638825 in words is "two hundred sixteen million, six hundred thirty-eight thousand, eight hundred twenty-five".