221992981 has 6 divisors (see below), whose sum is σ = 258236790. Its totient is φ = 190279656.

The previous prime is 221992937. The next prime is 221993003. The reversal of 221992981 is 189299122.

221992981 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It can be written as a sum of positive squares in only one way, i.e., 164096100 + 57896881 = 12810^2 + 7609^2 .

It is not a de Polignac number, because 221992981 - 2⁷ = 221992853 is a prime.

It is a super-2 number, since 2×221992981² = 98561767226532722, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (221992921) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 2265186 + ... + 2265283.

It is an arithmetic number, because the mean of its divisors is an integer number (43039465).

Almost surely, 2^221992981 is an apocalyptic number.

It is an amenable number.

221992981 is a deficient number, since it is larger than the sum of its proper divisors (36243809).

221992981 is an equidigital number, since it uses as much as digits as its factorization.

221992981 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4530483 (or 4530476 counting only the distinct ones).

The product of its digits is 46656, while the sum is 43.

The square root of 221992981 is about 14899.4288816719. The cubic root of 221992981 is about 605.4985131441.

The spelling of 221992981 in words is "two hundred twenty-one million, nine hundred ninety-two thousand, nine hundred eighty-one".