261421945 has 16 divisors (see below), whose sum is σ = 321930000. Its totient is φ = 203673600.

The previous prime is 261421883. The next prime is 261421957. The reversal of 261421945 is 549124162.

It can be written as a sum of positive squares in 8 ways, for example, as 31990336 + 229431609 = 5656^2 + 15147^2 .

It is not a de Polignac number, because 261421945 - 2¹³ = 261413753 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 261421945.

It is an unprimeable number.

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, 208681 + ... + 209929.

It is an arithmetic number, because the mean of its divisors is an integer number (20120625).

Almost surely, 2^261421945 is an apocalyptic number.

It is an amenable number.

261421945 is a deficient number, since it is larger than the sum of its proper divisors (60508055).

261421945 is a wasteful number, since it uses less digits than its factorization.

261421945 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2316.

The product of its digits is 17280, while the sum is 34.

The square root of 261421945 is about 16168.5480176793. The cubic root of 261421945 is about 639.4118498013.

The spelling of 261421945 in words is "two hundred sixty-one million, four hundred twenty-one thousand, nine hundred forty-five".