261216031 has 2 divisors, whose sum is σ = 261216032. Its totient is φ = 261216030.

The previous prime is 261216019. The next prime is 261216073. The reversal of 261216031 is 130612162.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 261216031 - 2¹¹ = 261213983 is a prime.

It is a super-2 number, since 2×261216031² = 136467629702785922, which contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 261215993 and 261216011.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (261216001) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 130608015 + 130608016.

It is an arithmetic number, because the mean of its divisors is an integer number (130608016).

Almost surely, 2^261216031 is an apocalyptic number.

261216031 is a deficient number, since it is larger than the sum of its proper divisors (1).

261216031 is an equidigital number, since it uses as much as digits as its factorization.

261216031 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 432, while the sum is 22.

The square root of 261216031 is about 16162.1790300689. The cubic root of 261216031 is about 639.2439240418.

Adding to 261216031 its reverse (130612162), we get a palindrome (391828193).

It can be divided in two parts, 26121 and 6031, that multiplied together give a palindrome (157535751).

The spelling of 261216031 in words is "two hundred sixty-one million, two hundred sixteen thousand, thirty-one".