261812611 has 4 divisors (see below), whose sum is σ = 273195792. Its totient is φ = 250429432.

The previous prime is 261812599. The next prime is 261812653. The reversal of 261812611 is 116218162.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 116218162 = 2 ⋅58109081.

It is a cyclic number.

It is not a de Polignac number, because 261812611 - 2²¹ = 259715459 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 261812611.

It is not an unprimeable number, because it can be changed into a prime (261812711) 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, 5691556 + ... + 5691601.

It is an arithmetic number, because the mean of its divisors is an integer number (68298948).

Almost surely, 2^261812611 is an apocalyptic number.

261812611 is a deficient number, since it is larger than the sum of its proper divisors (11383181).

261812611 is a wasteful number, since it uses less digits than its factorization.

261812611 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 11383180.

The product of its digits is 1152, while the sum is 28.

The square root of 261812611 is about 16180.6245553131. The cubic root of 261812611 is about 639.7302012209.

The spelling of 261812611 in words is "two hundred sixty-one million, eight hundred twelve thousand, six hundred eleven".