261810625 has 40 divisors (see below), whose sum is σ = 355442472. Its totient is φ = 192000000.

The previous prime is 261810623. The next prime is 261810629. The reversal of 261810625 is 526018162.

It can be written as a sum of positive squares in 20 ways, for example, as 255008961 + 6801664 = 15969^2 + 2608^2 .

It is not a de Polignac number, because 261810625 - 2¹ = 261810623 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (261810623) by changing a digit.

It is a polite number, since it can be written in 39 ways as a sum of consecutive naturals, for example, 435325 + ... + 435925.

Almost surely, 2^261810625 is an apocalyptic number.

261810625 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

It is an amenable number.

261810625 is a deficient number, since it is larger than the sum of its proper divisors (93631847).

261810625 is an equidigital number, since it uses as much as digits as its factorization.

261810625 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 679 (or 664 counting only the distinct ones).

The product of its (nonzero) digits is 5760, while the sum is 31.

The square root of 261810625 is about 16180.5631855013. The cubic root of 261810625 is about 639.7285836423.

Adding to 261810625 its reverse (526018162), we get a palindrome (787828787).

The spelling of 261810625 in words is "two hundred sixty-one million, eight hundred ten thousand, six hundred twenty-five".