261786545 has 4 divisors (see below), whose sum is σ = 314143860. Its totient is φ = 209429232.

The previous prime is 261786479. The next prime is 261786559. The reversal of 261786545 is 545687162.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 57410929 + 204375616 = 7577^2 + 14296^2 .

It is a cyclic number.

It is not a de Polignac number, because 261786545 - 2¹⁴ = 261770161 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 261786496 and 261786505.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 26178650 + ... + 26178659.

It is an arithmetic number, because the mean of its divisors is an integer number (78535965).

Almost surely, 2^261786545 is an apocalyptic number.

It is an amenable number.

261786545 is a deficient number, since it is larger than the sum of its proper divisors (52357315).

261786545 is an equidigital number, since it uses as much as digits as its factorization.

261786545 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 52357314.

The product of its digits is 403200, while the sum is 44.

The square root of 261786545 is about 16179.8190657374. The cubic root of 261786545 is about 639.7089700551.

It can be divided in two parts, 26178 and 6545, that added together give a palindrome (32723).

The spelling of 261786545 in words is "two hundred sixty-one million, seven hundred eighty-six thousand, five hundred forty-five".