261654665 has 4 divisors (see below), whose sum is σ = 313985604. Its totient is φ = 209323728.

The previous prime is 261654641. The next prime is 261654689. The reversal of 261654665 is 566456162.

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

It is an interprime number because it is at equal distance from previous prime (261654641) and next prime (261654689).

It can be written as a sum of positive squares in 2 ways, for example, as 38241856 + 223412809 = 6184^2 + 14947^2 .

It is a cyclic number.

It is not a de Polignac number, because 261654665 - 2⁸ = 261654409 is a prime.

It is a Duffinian number.

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, 26165462 + ... + 26165471.

It is an arithmetic number, because the mean of its divisors is an integer number (78496401).

Almost surely, 2^261654665 is an apocalyptic number.

It is an amenable number.

261654665 is a deficient number, since it is larger than the sum of its proper divisors (52330939).

261654665 is an equidigital number, since it uses as much as digits as its factorization.

261654665 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 52330938.

The product of its digits is 259200, while the sum is 41.

The square root of 261654665 is about 16175.7431050323. The cubic root of 261654665 is about 639.6015301180.

The spelling of 261654665 in words is "two hundred sixty-one million, six hundred fifty-four thousand, six hundred sixty-five".