261371901 has 16 divisors (see below), whose sum is σ = 403739264. Its totient is φ = 147308544.

The previous prime is 261371899. The next prime is 261371909. The reversal of 261371901 is 109173162.

It is not a de Polignac number, because 261371901 - 2¹ = 261371899 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (261371909) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 83716 + ... + 86781.

It is an arithmetic number, because the mean of its divisors is an integer number (25233704).

Almost surely, 2^261371901 is an apocalyptic number.

261371901 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

It is an amenable number.

261371901 is a deficient number, since it is larger than the sum of its proper divisors (142367363).

261371901 is a wasteful number, since it uses less digits than its factorization.

261371901 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 170580.

The product of its (nonzero) digits is 2268, while the sum is 30.

The square root of 261371901 is about 16167.0003711264. Note that the first 3 decimals coincide. The cubic root of 261371901 is about 639.3710463297.

The spelling of 261371901 in words is "two hundred sixty-one million, three hundred seventy-one thousand, nine hundred one".