221999981 has 8 divisors (see below), whose sum is σ = 253899840. Its totient is φ = 190146528.

The previous prime is 221999929. The next prime is 221999983. The reversal of 221999981 is 189999122.

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 221999981 - 2¹⁰ = 221998957 is a prime.

It is a super-2 number, since 2×221999981² = 98567983128000722, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (221999983) 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, 656 + ... + 21081.

It is an arithmetic number, because the mean of its divisors is an integer number (31737480).

Almost surely, 2^221999981 is an apocalyptic number.

It is an amenable number.

221999981 is a deficient number, since it is larger than the sum of its proper divisors (31899859).

221999981 is a wasteful number, since it uses less digits than its factorization.

221999981 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 23203.

The product of its digits is 209952, while the sum is 50.

The square root of 221999981 is about 14899.6637881531. The cubic root of 221999981 is about 605.5048773769.

The spelling of 221999981 in words is "two hundred twenty-one million, nine hundred ninety-nine thousand, nine hundred eighty-one".