261145166 has 4 divisors (see below), whose sum is σ = 391717752. Its totient is φ = 130572582.

The previous prime is 261145127. The next prime is 261145187. The reversal of 261145166 is 661541162.

It is a semiprime because it is the product of two primes.

It is a Curzon number.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 65286290 + ... + 65286293.

It is an arithmetic number, because the mean of its divisors is an integer number (97929438).

Almost surely, 2^261145166 is an apocalyptic number.

261145166 is a deficient number, since it is larger than the sum of its proper divisors (130572586).

261145166 is a wasteful number, since it uses less digits than its factorization.

261145166 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 130572585.

The product of its digits is 8640, while the sum is 32.

The square root of 261145166 is about 16159.9865717766. The cubic root of 261145166 is about 639.1861122279.

The spelling of 261145166 in words is "two hundred sixty-one million, one hundred forty-five thousand, one hundred sixty-six".