261243225 has 36 divisors (see below), whose sum is σ = 485257136. Its totient is φ = 139326480.

The previous prime is 261243221. The next prime is 261243239. The reversal of 261243225 is 522342162.

It is a happy number.

261243225 is a `hidden beast` number, since 2 + 612 + 43 + 2 + 2 + 5 = 666.

It is not a de Polignac number, because 261243225 - 2² = 261243221 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (261243221) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 35 ways as a sum of consecutive naturals, for example, 15427 + ... + 27576.

Almost surely, 2^261243225 is an apocalyptic number.

261243225 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

It is an amenable number.

261243225 is a deficient number, since it is larger than the sum of its proper divisors (224013911).

261243225 is an equidigital number, since it uses as much as digits as its factorization.

261243225 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 43028 (or 43011 counting only the distinct ones).

The product of its digits is 5760, while the sum is 27.

The square root of 261243225 is about 16163.0202932496. The cubic root of 261243225 is about 639.2661061874.

Adding to 261243225 its reverse (522342162), we get a palindrome (783585387).

The spelling of 261243225 in words is "two hundred sixty-one million, two hundred forty-three thousand, two hundred twenty-five".