261699409 has 6 divisors (see below), whose sum is σ = 268964934. Its totient is φ = 254625120.

The previous prime is 261699401. The next prime is 261699443. The reversal of 261699409 is 904996162.

It can be written as a sum of positive squares in 3 ways, for example, as 216001809 + 45697600 = 14697^2 + 6760^2 .

It is not a de Polignac number, because 261699409 - 2³ = 261699401 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (261699401) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 94212 + ... + 96949.

It is an arithmetic number, because the mean of its divisors is an integer number (44827489).

Almost surely, 2^261699409 is an apocalyptic number.

It is an amenable number.

261699409 is a deficient number, since it is larger than the sum of its proper divisors (7265525).

261699409 is an equidigital number, since it uses as much as digits as its factorization.

261699409 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 191235 (or 191198 counting only the distinct ones).

The product of its (nonzero) digits is 209952, while the sum is 46.

The square root of 261699409 is about 16177.1261044723. The cubic root of 261699409 is about 639.6379861847.

The spelling of 261699409 in words is "two hundred sixty-one million, six hundred ninety-nine thousand, four hundred nine".