261551545 has 16 divisors (see below), whose sum is σ = 332948880. Its totient is φ = 196562944.

The previous prime is 261551539. The next prime is 261551567. The reversal of 261551545 is 545155162.

It can be written as a sum of positive squares in 8 ways, for example, as 21270544 + 240281001 = 4612^2 + 15501^2 .

It is a cyclic number.

It is not a de Polignac number, because 261551545 - 2⁵ = 261551513 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 261551545.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 47811 + ... + 52999.

It is an arithmetic number, because the mean of its divisors is an integer number (20809305).

Almost surely, 2^261551545 is an apocalyptic number.

It is an amenable number.

261551545 is a deficient number, since it is larger than the sum of its proper divisors (71397335).

261551545 is a wasteful number, since it uses less digits than its factorization.

261551545 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5804.

The product of its digits is 30000, while the sum is 34.

The square root of 261551545 is about 16172.5553021160. Note that the first 3 decimals coincide. The cubic root of 261551545 is about 639.5174952111.

The spelling of 261551545 in words is "two hundred sixty-one million, five hundred fifty-one thousand, five hundred forty-five".