261640777 has 8 divisors (see below), whose sum is σ = 263554560. Its totient is φ = 259733040.

The previous prime is 261640759. The next prime is 261640781. The reversal of 261640777 is 777046162.

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-261640777 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (261640177) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 117123 + ... + 119335.

It is an arithmetic number, because the mean of its divisors is an integer number (32944320).

Almost surely, 2^261640777 is an apocalyptic number.

It is an amenable number.

261640777 is a deficient number, since it is larger than the sum of its proper divisors (1913783).

261640777 is a wasteful number, since it uses less digits than its factorization.

261640777 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3023.

The product of its (nonzero) digits is 98784, while the sum is 40.

The square root of 261640777 is about 16175.3138145756. The cubic root of 261640777 is about 639.5902137478.

The spelling of 261640777 in words is "two hundred sixty-one million, six hundred forty thousand, seven hundred seventy-seven".