261651166625 has 8 divisors (see below), whose sum is σ = 326540656104. Its totient is φ = 209320933200.

The previous prime is 261651166561. The next prime is 261651166657. The reversal of 261651166625 is 526661156162.

It can be written as a sum of positive squares in 4 ways, for example, as 14531820304 + 247119346321 = 120548^2 + 497111^2 .

It is not a de Polignac number, because 261651166625 - 2⁶ = 261651166561 is a prime.

It is a super-2 number, since 2×261651166625² (a number of 24 digits) contains 22 as substring.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 261651166625.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1046604542 + ... + 1046604791.

It is an arithmetic number, because the mean of its divisors is an integer number (40817582013).

Almost surely, 2^261651166625 is an apocalyptic number.

261651166625 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

It is an amenable number.

261651166625 is a deficient number, since it is larger than the sum of its proper divisors (64889489479).

261651166625 is an equidigital number, since it uses as much as digits as its factorization.

261651166625 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2093209348 (or 2093209338 counting only the distinct ones).

The product of its digits is 777600, while the sum is 47.

The spelling of 261651166625 in words is "two hundred sixty-one billion, six hundred fifty-one million, one hundred sixty-six thousand, six hundred twenty-five".