221681881 has 8 divisors (see below), whose sum is σ = 226142280. Its totient is φ = 217231872.

The previous prime is 221681861. The next prime is 221681891. The reversal of 221681881 is 188186122.

It is a happy number.

It can be written as a sum of positive squares in 4 ways, for example, as 5856400 + 215825481 = 2420^2 + 14691^2 .

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

It is a cyclic number.

It is not a de Polignac number, because 221681881 - 2¹¹ = 221679833 is a prime.

It is a super-2 number, since 2×221681881² = 98285712727396322, which contains 22 as substring.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 221681881.

It is not an unprimeable number, because it can be changed into a prime (221681861) 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, 51625 + ... + 55753.

It is an arithmetic number, because the mean of its divisors is an integer number (28267785).

Almost surely, 2^221681881 is an apocalyptic number.

It is an amenable number.

221681881 is a deficient number, since it is larger than the sum of its proper divisors (4460399).

221681881 is a wasteful number, since it uses less digits than its factorization.

221681881 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5195.

The product of its digits is 12288, while the sum is 37.

The square root of 221681881 is about 14888.9852239835. The cubic root of 221681881 is about 605.2155332513.

The spelling of 221681881 in words is "two hundred twenty-one million, six hundred eighty-one thousand, eight hundred eighty-one".