261806345 has 8 divisors (see below), whose sum is σ = 325001160. Its totient is φ = 202222720.

The previous prime is 261806329. The next prime is 261806351. The reversal of 261806345 is 543608162.

It can be written as a sum of positive squares in 4 ways, for example, as 9504889 + 252301456 = 3083^2 + 15884^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 261806345 - 2⁴ = 261806329 is a prime.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 902636 + ... + 902925.

It is an arithmetic number, because the mean of its divisors is an integer number (40625145).

Almost surely, 2^261806345 is an apocalyptic number.

It is an amenable number.

261806345 is a deficient number, since it is larger than the sum of its proper divisors (63194815).

261806345 is a wasteful number, since it uses less digits than its factorization.

261806345 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1805595.

The product of its (nonzero) digits is 34560, while the sum is 35.

The square root of 261806345 is about 16180.4309275124. The cubic root of 261806345 is about 639.7250975943.

The spelling of 261806345 in words is "two hundred sixty-one million, eight hundred six thousand, three hundred forty-five".