261859221 has 12 divisors (see below), whose sum is σ = 407336748. Its totient is φ = 161144064.

The previous prime is 261859219. The next prime is 261859223. The reversal of 261859221 is 122958162.

261859221 is a `hidden beast` number, since 2 + 61 + 8 + 592 + 2 + 1 = 666.

It is an interprime number because it is at equal distance from previous prime (261859219) and next prime (261859223).

It can be written as a sum of positive squares in 2 ways, for example, as 105884100 + 155975121 = 10290^2 + 12489^2 .

It is not a de Polignac number, because 261859221 - 2¹ = 261859219 is a prime.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (261859223) 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, 1118940 + ... + 1119173.

It is an arithmetic number, because the mean of its divisors is an integer number (33944729).

Almost surely, 2^261859221 is an apocalyptic number.

It is an amenable number.

261859221 is a deficient number, since it is larger than the sum of its proper divisors (145477527).

261859221 is a wasteful number, since it uses less digits than its factorization.

261859221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2238132 (or 2238129 counting only the distinct ones).

The product of its digits is 17280, while the sum is 36.

The square root of 261859221 is about 16182.0647940861. The cubic root of 261859221 is about 639.7681622843.

The spelling of 261859221 in words is "two hundred sixty-one million, eight hundred fifty-nine thousand, two hundred twenty-one".