261818081 has 16 divisors (see below), whose sum is σ = 315432960. Its totient is φ = 212291280.

The previous prime is 261818057. The next prime is 261818101. The reversal of 261818081 is 180818162.

It is a cyclic number.

It is not a de Polignac number, because 261818081 - 2²⁶ = 194709217 is a prime.

It is a super-2 number, since 2×261818081² = 137097415077045122, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (261818681) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 143666 + ... + 145476.

It is an arithmetic number, because the mean of its divisors is an integer number (19714560).

Almost surely, 2^261818081 is an apocalyptic number.

It is an amenable number.

261818081 is a deficient number, since it is larger than the sum of its proper divisors (53614879).

261818081 is a wasteful number, since it uses less digits than its factorization.

261818081 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2924.

The product of its (nonzero) digits is 6144, while the sum is 35.

The square root of 261818081 is about 16180.7935837523. The cubic root of 261818081 is about 639.7346564428.

The spelling of 261818081 in words is "two hundred sixty-one million, eight hundred eighteen thousand, eighty-one".