261766211507 has 4 divisors (see below), whose sum is σ = 262761520560. Its totient is φ = 260770902456.

The previous prime is 261766211423. The next prime is 261766211521. The reversal of 261766211507 is 705112667162.

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 261766211507 - 2¹⁰ = 261766210483 is a prime.

It is a super-2 number, since 2×261766211507² (a number of 24 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (261766211537) 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, 497654132 + ... + 497654657.

It is an arithmetic number, because the mean of its divisors is an integer number (65690380140).

Almost surely, 2^261766211507 is an apocalyptic number.

261766211507 is a deficient number, since it is larger than the sum of its proper divisors (995309053).

261766211507 is an equidigital number, since it uses as much as digits as its factorization.

261766211507 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 995309052.

The product of its (nonzero) digits is 211680, while the sum is 44.

Adding to 261766211507 its reverse (705112667162), we get a palindrome (966878878669).

The spelling of 261766211507 in words is "two hundred sixty-one billion, seven hundred sixty-six million, two hundred eleven thousand, five hundred seven".