865477561 has 27 divisors (see below), whose sum is σ = 981827757. Its totient is φ = 762540480.

The previous prime is 865477541. The next prime is 865477579. The reversal of 865477561 is 165774568.

It is a happy number.

The square root of 865477561 is 29419.

It is a perfect power (a square), and thus also a powerful number.

It can be written as a sum of positive squares in 4 ways, for example, as 87067561 + 778410000 = 9331^2 + 27900^2 .

It is not a de Polignac number, because 865477561 - 2²¹ = 863380409 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (865477541) by changing a digit.

It is a polite number, since it can be written in 26 ways as a sum of consecutive naturals, for example, 11855821 + ... + 11855893.

It is an arithmetic number, because the mean of its divisors is an integer number (36363991).

Almost surely, 2^865477561 is an apocalyptic number.

865477561 is the 29419-th square number.

865477561 is the 14710-th centered octagonal number.

It is an amenable number.

865477561 is a deficient number, since it is larger than the sum of its proper divisors (116350196).

865477561 is an equidigital number, since it uses as much as digits as its factorization.

865477561 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 234 (or 117 counting only the distinct ones).

The product of its digits is 1411200, while the sum is 49.

The cubic root of 865477561 is about 952.9832575977.

Multiplying 865477561 by its sum of digits (49), we get a square (42408400489 = 205933²).

The spelling of 865477561 in words is "eight hundred sixty-five million, four hundred seventy-seven thousand, five hundred sixty-one".