261222813 has 12 divisors (see below), whose sum is σ = 391297088. Its totient is φ = 174148380.

The previous prime is 261222809. The next prime is 261222817. The reversal of 261222813 is 318222162.

It is an interprime number because it is at equal distance from previous prime (261222809) and next prime (261222817).

It is not a de Polignac number, because 261222813 - 2² = 261222809 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (261222817) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 537253 + ... + 537738.

Almost surely, 2^261222813 is an apocalyptic number.

It is an amenable number.

261222813 is a deficient number, since it is larger than the sum of its proper divisors (130074275).

261222813 is an equidigital number, since it uses as much as digits as its factorization.

261222813 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1075006 (or 1074994 counting only the distinct ones).

The product of its digits is 2304, while the sum is 27.

The square root of 261222813 is about 16162.3888395249. The cubic root of 261222813 is about 639.2494562632.

Adding to 261222813 its reverse (318222162), we get a palindrome (579444975).

It can be divided in two parts, 2612 and 22813, that added together give a triangular number (25425 = T₂₂₅).

The spelling of 261222813 in words is "two hundred sixty-one million, two hundred twenty-two thousand, eight hundred thirteen".