261099605 has 8 divisors (see below), whose sum is σ = 337421112. Its totient is φ = 192811968.

The previous prime is 261099599. The next prime is 261099649. The reversal of 261099605 is 506990162.

It can be written as a sum of positive squares in 4 ways, for example, as 24462916 + 236636689 = 4946^2 + 15383^2 .

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

It is a cyclic number.

It is not a de Polignac number, because 261099605 - 2¹² = 261095509 is a prime.

It is a Duffinian number.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 2008394 + ... + 2008523.

It is an arithmetic number, because the mean of its divisors is an integer number (42177639).

Almost surely, 2^261099605 is an apocalyptic number.

It is an amenable number.

261099605 is a deficient number, since it is larger than the sum of its proper divisors (76321507).

261099605 is a wasteful number, since it uses less digits than its factorization.

261099605 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4016935.

The product of its (nonzero) digits is 29160, while the sum is 38.

The square root of 261099605 is about 16158.5768247083. The cubic root of 261099605 is about 639.1489379457.

The spelling of 261099605 in words is "two hundred sixty-one million, ninety-nine thousand, six hundred five".