261065531 has 4 divisors (see below), whose sum is σ = 262508064. Its totient is φ = 259623000.

The previous prime is 261065521. The next prime is 261065557. The reversal of 261065531 is 135560162.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 261065531 - 2¹⁴ = 261049147 is a prime.

It is a super-2 number, since 2×261065531² = 136310422952623922, which contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 261065494 and 261065503.

It is not an unprimeable number, because it can be changed into a prime (261065521) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 720995 + ... + 721356.

It is an arithmetic number, because the mean of its divisors is an integer number (65627016).

Almost surely, 2^261065531 is an apocalyptic number.

261065531 is a deficient number, since it is larger than the sum of its proper divisors (1442533).

261065531 is a wasteful number, since it uses less digits than its factorization.

261065531 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1442532.

The product of its (nonzero) digits is 5400, while the sum is 29.

The square root of 261065531 is about 16157.5224276496. The cubic root of 261065531 is about 639.1211333481.

The spelling of 261065531 in words is "two hundred sixty-one million, sixty-five thousand, five hundred thirty-one".