221555549 has 2 divisors, whose sum is σ = 221555550. Its totient is φ = 221555548.

The previous prime is 221555539. The next prime is 221555557. The reversal of 221555549 is 945555122.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 202151524 + 19404025 = 14218^2 + 4405^2 .

It is a cyclic number.

It is not a de Polignac number, because 221555549 - 2¹⁶ = 221490013 is a prime.

It is a super-2 number, since 2×221555549² = 98173722585382802, which contains 22 as substring.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (221555539) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 110777774 + 110777775.

It is an arithmetic number, because the mean of its divisors is an integer number (110777775).

Almost surely, 2^221555549 is an apocalyptic number.

It is an amenable number.

221555549 is a deficient number, since it is larger than the sum of its proper divisors (1).

221555549 is an equidigital number, since it uses as much as digits as its factorization.

221555549 is an evil number, because the sum of its binary digits is even.

The product of its digits is 90000, while the sum is 38.

The square root of 221555549 is about 14884.7421543002. The cubic root of 221555549 is about 605.1005447266.

The spelling of 221555549 in words is "two hundred twenty-one million, five hundred fifty-five thousand, five hundred forty-nine".