261565930 has 16 divisors (see below), whose sum is σ = 471293064. Its totient is φ = 104520960.

The previous prime is 261565907. The next prime is 261565933. The reversal of 261565930 is 39565162.

It is a Cunningham number, because it is equal to 16173²+1.

It can be written as a sum of positive squares in 4 ways, for example, as 261565929 + 1 = 16173^2 + 1^2 .

It is a self number, because there is not a number n which added to its sum of digits gives 261565930.

It is not an unprimeable number, because it can be changed into a prime (261565933) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 2331 + ... + 22990.

Almost surely, 2^261565930 is an apocalyptic number.

261565930 is a deficient number, since it is larger than the sum of its proper divisors (209727134).

261565930 is a wasteful number, since it uses less digits than its factorization.

261565930 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 26361.

The product of its (nonzero) digits is 48600, while the sum is 37.

The square root of 261565930 is about 16173.0000309157. Note that the first 4 decimals coincide. The cubic root of 261565930 is about 639.5292192106.

The spelling of 261565930 in words is "two hundred sixty-one million, five hundred sixty-five thousand, nine hundred thirty".