261601065 has 24 divisors (see below), whose sum is σ = 494664768. Its totient is φ = 126836640.

The previous prime is 261601061. The next prime is 261601069. The reversal of 261601065 is 560106162.

It is a happy number.

It is an interprime number because it is at equal distance from previous prime (261601061) and next prime (261601069).

It is not a de Polignac number, because 261601065 - 2² = 261601061 is a prime.

It is not an unprimeable number, because it can be changed into a prime (261601061) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 263749 + ... + 264738.

It is an arithmetic number, because the mean of its divisors is an integer number (20611032).

Almost surely, 2^261601065 is an apocalyptic number.

It is an amenable number.

261601065 is a deficient number, since it is larger than the sum of its proper divisors (233063703).

261601065 is a wasteful number, since it uses less digits than its factorization.

261601065 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 528509 (or 528506 counting only the distinct ones).

The product of its (nonzero) digits is 2160, while the sum is 27.

The square root of 261601065 is about 16174.0862183927. The cubic root of 261601065 is about 639.5578529769.

It can be divided in two parts, 26160 and 1065, that added together give a square (27225 = 165²).

The spelling of 261601065 in words is "two hundred sixty-one million, six hundred one thousand, sixty-five".