261851801 has 2 divisors, whose sum is σ = 261851802. Its totient is φ = 261851800.

The previous prime is 261851771. The next prime is 261851819. The reversal of 261851801 is 108158162.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 214915600 + 46936201 = 14660^2 + 6851^2 .

It is a cyclic number.

It is not a de Polignac number, because 261851801 - 2¹⁰ = 261850777 is a prime.

It is not a weakly prime, because it can be changed into another prime (261851831) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 130925900 + 130925901.

It is an arithmetic number, because the mean of its divisors is an integer number (130925901).

Almost surely, 2^261851801 is an apocalyptic number.

It is an amenable number.

261851801 is a deficient number, since it is larger than the sum of its proper divisors (1).

261851801 is an equidigital number, since it uses as much as digits as its factorization.

261851801 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 3840, while the sum is 32.

The square root of 261851801 is about 16181.8355262931. The cubic root of 261851801 is about 639.7621194386.

The spelling of 261851801 in words is "two hundred sixty-one million, eight hundred fifty-one thousand, eight hundred one".