261220166 has 8 divisors (see below), whose sum is σ = 391905000. Its totient is φ = 130585168.

The previous prime is 261220153. The next prime is 261220187. The reversal of 261220166 is 661022162.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 6290 + ... + 23706.

It is an arithmetic number, because the mean of its divisors is an integer number (48988125).

Almost surely, 2^261220166 is an apocalyptic number.

261220166 is a deficient number, since it is larger than the sum of its proper divisors (130684834).

261220166 is a wasteful number, since it uses less digits than its factorization.

261220166 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 24918.

The product of its (nonzero) digits is 1728, while the sum is 26.

The square root of 261220166 is about 16162.3069516700. The cubic root of 261220166 is about 639.2472970605.

The spelling of 261220166 in words is "two hundred sixty-one million, two hundred twenty thousand, one hundred sixty-six".