261764661 has 8 divisors (see below), whose sum is σ = 351531040. Its totient is φ = 173254032.

The previous prime is 261764639. The next prime is 261764669. The reversal of 261764661 is 166467162.

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

It is not a de Polignac number, because 261764661 - 2⁶ = 261764597 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (261764669) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 313450 + ... + 314283.

It is an arithmetic number, because the mean of its divisors is an integer number (43941380).

Almost surely, 2^261764661 is an apocalyptic number.

It is an amenable number.

261764661 is a deficient number, since it is larger than the sum of its proper divisors (89766379).

261764661 is a wasteful number, since it uses less digits than its factorization.

261764661 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 627875.

The product of its digits is 72576, while the sum is 39.

The square root of 261764661 is about 16179.1427770448. The cubic root of 261764661 is about 639.6911441055.

The spelling of 261764661 in words is "two hundred sixty-one million, seven hundred sixty-four thousand, six hundred sixty-one".