221706861 has 16 divisors (see below), whose sum is σ = 299920320. Its totient is φ = 145658240.

The previous prime is 221706857. The next prime is 221706871. The reversal of 221706861 is 168607122.

It is a cyclic number.

It is not a de Polignac number, because 221706861 - 2² = 221706857 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (221706811) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 128875 + ... + 130583.

It is an arithmetic number, because the mean of its divisors is an integer number (18745020).

Almost surely, 2^221706861 is an apocalyptic number.

It is an amenable number.

221706861 is a deficient number, since it is larger than the sum of its proper divisors (78213459).

221706861 is a wasteful number, since it uses less digits than its factorization.

221706861 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2316.

The product of its (nonzero) digits is 8064, while the sum is 33.

The square root of 221706861 is about 14889.8240755222. The cubic root of 221706861 is about 605.2382650989.

The spelling of 221706861 in words is "two hundred twenty-one million, seven hundred six thousand, eight hundred sixty-one".