261757661 has 8 divisors (see below), whose sum is σ = 300583200. Its totient is φ = 225437040.

The previous prime is 261757621. The next prime is 261757697. The reversal of 261757661 is 166757162.

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 261757661 - 2⁶ = 261757597 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (261757621) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 626006 + ... + 626423.

It is an arithmetic number, because the mean of its divisors is an integer number (37572900).

Almost surely, 2^261757661 is an apocalyptic number.

It is an amenable number.

261757661 is a deficient number, since it is larger than the sum of its proper divisors (38825539).

261757661 is a wasteful number, since it uses less digits than its factorization.

261757661 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1252459.

The product of its digits is 105840, while the sum is 41.

The square root of 261757661 is about 16178.9264476973. The cubic root of 261757661 is about 639.6854419379.

The spelling of 261757661 in words is "two hundred sixty-one million, seven hundred fifty-seven thousand, six hundred sixty-one".