221658993 has 6 divisors (see below), whose sum is σ = 320174114. Its totient is φ = 147772656.

The previous prime is 221658989. The next prime is 221659007. The reversal of 221658993 is 399856122.

It can be written as a sum of positive squares in only one way, i.e., 219721329 + 1937664 = 14823^2 + 1392^2 .

It is not a de Polignac number, because 221658993 - 2² = 221658989 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (221658923) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 12314380 + ... + 12314397.

Almost surely, 2^221658993 is an apocalyptic number.

It is an amenable number.

221658993 is a deficient number, since it is larger than the sum of its proper divisors (98515121).

221658993 is a wasteful number, since it uses less digits than its factorization.

221658993 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 24628783 (or 24628780 counting only the distinct ones).

The product of its digits is 233280, while the sum is 45.

The square root of 221658993 is about 14888.2165822505. The cubic root of 221658993 is about 605.1947036285.

The spelling of 221658993 in words is "two hundred twenty-one million, six hundred fifty-eight thousand, nine hundred ninety-three".