261099217 has 2 divisors, whose sum is σ = 261099218. Its totient is φ = 261099216.

The previous prime is 261099199. The next prime is 261099257. The reversal of 261099217 is 712990162.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 217592001 + 43507216 = 14751^2 + 6596^2 .

It is a cyclic number.

It is not a de Polignac number, because 261099217 - 2²³ = 252710609 is a prime.

It is a super-2 number, since 2×261099217² = 136345602236026178, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (261099257) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 130549608 + 130549609.

It is an arithmetic number, because the mean of its divisors is an integer number (130549609).

Almost surely, 2^261099217 is an apocalyptic number.

It is an amenable number.

261099217 is a deficient number, since it is larger than the sum of its proper divisors (1).

261099217 is an equidigital number, since it uses as much as digits as its factorization.

261099217 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 13608, while the sum is 37.

The square root of 261099217 is about 16158.5648186960. The cubic root of 261099217 is about 639.1486213489.

The spelling of 261099217 in words is "two hundred sixty-one million, ninety-nine thousand, two hundred seventeen".