221510225 has 12 divisors (see below), whose sum is σ = 276839424. Its totient is φ = 175810320.

The previous prime is 221510213. The next prime is 221510257. The reversal of 221510225 is 522015122.

It is a happy number.

It is a de Polignac number, because none of the positive numbers 2^k-221510225 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 221510197 and 221510206.

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, 31709 + ... + 38058.

It is an arithmetic number, because the mean of its divisors is an integer number (23069952).

Almost surely, 2^221510225 is an apocalyptic number.

221510225 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

It is an amenable number.

221510225 is a deficient number, since it is larger than the sum of its proper divisors (55329199).

221510225 is a wasteful number, since it uses less digits than its factorization.

221510225 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 69904 (or 69899 counting only the distinct ones).

The product of its (nonzero) digits is 400, while the sum is 20.

The square root of 221510225 is about 14883.2195777661. The cubic root of 221510225 is about 605.0592797593.

Adding to 221510225 its reverse (522015122), we get a palindrome (743525347).

The spelling of 221510225 in words is "two hundred twenty-one million, five hundred ten thousand, two hundred twenty-five".