221481993 has 16 divisors (see below), whose sum is σ = 311386880. Its totient is φ = 139642704.

The previous prime is 221481989. The next prime is 221482003. The reversal of 221481993 is 399184122.

It is not a de Polignac number, because 221481993 - 2² = 221481989 is a prime.

It is a Smith number, since the sum of its digits (39) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (221481493) 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, 33630 + ... + 39672.

It is an arithmetic number, because the mean of its divisors is an integer number (19461680).

Almost surely, 2^221481993 is an apocalyptic number.

It is an amenable number.

221481993 is a deficient number, since it is larger than the sum of its proper divisors (89904887).

221481993 is a wasteful number, since it uses less digits than its factorization.

221481993 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6708.

The product of its digits is 31104, while the sum is 39.

The square root of 221481993 is about 14882.2710968454. The cubic root of 221481993 is about 605.0335732570.

The spelling of 221481993 in words is "two hundred twenty-one million, four hundred eighty-one thousand, nine hundred ninety-three".