261553775447225 has 6 divisors (see below), whose sum is σ = 324326681554590. Its totient is φ = 209243020357760.

The previous prime is 261553775447183. The next prime is 261553775447249. The reversal of 261553775447225 is 522744577355162.

It can be written as a sum of positive squares in 3 ways, for example, as 1099752813481 + 260454022633744 = 1048691^2 + 16138588^2 .

It is not a de Polignac number, because 261553775447225 - 2¹⁸ = 261553775185081 is a prime.

It is an unprimeable number.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 5231075508920 + ... + 5231075508969.

It is an arithmetic number, because the mean of its divisors is an integer number (54054446925765).

Almost surely, 2^{261553775447225} is an apocalyptic number.

261553775447225 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

It is an amenable number.

261553775447225 is a deficient number, since it is larger than the sum of its proper divisors (62772906107365).

261553775447225 is a wasteful number, since it uses less digits than its factorization.

261553775447225 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10462151017899 (or 10462151017894 counting only the distinct ones).

The product of its digits is 493920000, while the sum is 65.

The spelling of 261553775447225 in words is "two hundred sixty-one trillion, five hundred fifty-three billion, seven hundred seventy-five million, four hundred forty-seven thousand, two hundred twenty-five".