221824981 has 16 divisors (see below), whose sum is σ = 271900800. Its totient is φ = 176724288.

The previous prime is 221824979. The next prime is 221824991. The reversal of 221824981 is 189428122.

It is a happy number.

It is a cyclic number.

It is not a de Polignac number, because 221824981 - 2¹ = 221824979 is a prime.

It is a super-2 number, since 2×221824981² = 98412644391300722, 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 221824981.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (221824921) 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, 8686 + ... + 22783.

It is an arithmetic number, because the mean of its divisors is an integer number (16993800).

Almost surely, 2^221824981 is an apocalyptic number.

It is an amenable number.

221824981 is a deficient number, since it is larger than the sum of its proper divisors (50075819).

221824981 is a wasteful number, since it uses less digits than its factorization.

221824981 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 31548.

The product of its digits is 18432, while the sum is 37.

The square root of 221824981 is about 14893.7900146336. The cubic root of 221824981 is about 605.3457314039.

The spelling of 221824981 in words is "two hundred twenty-one million, eight hundred twenty-four thousand, nine hundred eighty-one".