261421726237165 has 32 divisors (see below), whose sum is σ = 341910743328000. Its totient is φ = 190722254946816.

The previous prime is 261421726237129. The next prime is 261421726237183. The reversal of 261421726237165 is 561732627124162.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-261421726237165 is a prime.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 1177342344 + ... + 1177564366.

It is an arithmetic number, because the mean of its divisors is an integer number (10684710729000).

Almost surely, 2^{261421726237165} is an apocalyptic number.

It is an amenable number.

261421726237165 is a deficient number, since it is larger than the sum of its proper divisors (80489017090835).

261421726237165 is a wasteful number, since it uses less digits than its factorization.

261421726237165 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 440373.

The product of its digits is 10160640, while the sum is 55.

The spelling of 261421726237165 in words is "two hundred sixty-one trillion, four hundred twenty-one billion, seven hundred twenty-six million, two hundred thirty-seven thousand, one hundred sixty-five".