261618837225 has 12 divisors (see below), whose sum is σ = 432543144336. Its totient is φ = 139530046480.

The previous prime is 261618837203. The next prime is 261618837247. The reversal of 261618837225 is 522738816162.

It is an interprime number because it is at equal distance from previous prime (261618837203) and next prime (261618837247).

It is not a de Polignac number, because 261618837225 - 2¹⁹ = 261618312937 is a prime.

It is a super-2 number, since 2×261618837225² (a number of 24 digits) contains 22 as substring.

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, 1744125507 + ... + 1744125656.

It is an arithmetic number, because the mean of its divisors is an integer number (36045262028).

Almost surely, 2^261618837225 is an apocalyptic number.

261618837225 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

It is an amenable number.

261618837225 is a deficient number, since it is larger than the sum of its proper divisors (170924307111).

261618837225 is a wasteful number, since it uses less digits than its factorization.

261618837225 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3488251176 (or 3488251171 counting only the distinct ones).

The product of its digits is 1935360, while the sum is 51.

The spelling of 261618837225 in words is "two hundred sixty-one billion, six hundred eighteen million, eight hundred thirty-seven thousand, two hundred twenty-five".