261645385 has 16 divisors (see below), whose sum is σ = 337412736. Its totient is φ = 194059008.

The previous prime is 261645379. The next prime is 261645403. The reversal of 261645385 is 583546162.

It is a cyclic number.

It is not a de Polignac number, because 261645385 - 2¹³ = 261637193 is a prime.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 17277 + ... + 28666.

It is an arithmetic number, because the mean of its divisors is an integer number (21088296).

Almost surely, 2^261645385 is an apocalyptic number.

It is an amenable number.

261645385 is a deficient number, since it is larger than the sum of its proper divisors (75767351).

261645385 is a wasteful number, since it uses less digits than its factorization.

261645385 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 46032.

The product of its digits is 172800, while the sum is 40.

The square root of 261645385 is about 16175.4562532251. The cubic root of 261645385 is about 639.5939685325.

The spelling of 261645385 in words is "two hundred sixty-one million, six hundred forty-five thousand, three hundred eighty-five".