261445261 has 16 divisors (see below), whose sum is σ = 345133440. Its totient is φ = 191738880.

The previous prime is 261445141. The next prime is 261445271. The reversal of 261445261 is 162544162.

It is a happy number.

It is a cyclic number.

It is not a de Polignac number, because 261445261 - 2¹³ = 261437069 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 (261445271) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 98556 + ... + 101173.

It is an arithmetic number, because the mean of its divisors is an integer number (21570840).

Almost surely, 2^261445261 is an apocalyptic number.

It is an amenable number.

261445261 is a deficient number, since it is larger than the sum of its proper divisors (83688179).

261445261 is a wasteful number, since it uses less digits than its factorization.

261445261 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 199764.

The product of its digits is 11520, while the sum is 31.

The square root of 261445261 is about 16169.2690310972. The cubic root of 261445261 is about 639.4308587684.

The spelling of 261445261 in words is "two hundred sixty-one million, four hundred forty-five thousand, two hundred sixty-one".