261800001 has 12 divisors (see below), whose sum is σ = 378399060. Its totient is φ = 174420960.

The previous prime is 261799969. The next prime is 261800009. The reversal of 261800001 is 100008162.

It can be written as a sum of positive squares in 2 ways, for example, as 167029776 + 94770225 = 12924^2 + 9735^2 .

It is not a de Polignac number, because 261800001 - 2⁵ = 261799969 is a prime.

It is not an unprimeable number, because it can be changed into a prime (261800009) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 6871 + ... + 23891.

It is an arithmetic number, because the mean of its divisors is an integer number (31533255).

Almost surely, 2^261800001 is an apocalyptic number.

It is an amenable number.

261800001 is a deficient number, since it is larger than the sum of its proper divisors (116599059).

261800001 is a wasteful number, since it uses less digits than its factorization.

261800001 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 18736 (or 18733 counting only the distinct ones).

The product of its (nonzero) digits is 96, while the sum is 18.

The square root of 261800001 is about 16180.2348870466. The cubic root of 261800001 is about 639.7199303541.

Adding to 261800001 its reverse (100008162), we get a palindrome (361808163).

The spelling of 261800001 in words is "two hundred sixty-one million, eight hundred thousand, one".