221379281 has 2 divisors, whose sum is σ = 221379282. Its totient is φ = 221379280.

The previous prime is 221379233. The next prime is 221379293. The reversal of 221379281 is 182973122.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 155850256 + 65529025 = 12484^2 + 8095^2 .

It is a cyclic number.

It is not a de Polignac number, because 221379281 - 2⁶ = 221379217 is a prime.

It is a super-4 number, since 4×221379281⁴ (a number of 34 digits) contains 4444 as substring. Note that it is a super-d number also for d = 2.

It is not a weakly prime, because it can be changed into another prime (221379211) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 110689640 + 110689641.

It is an arithmetic number, because the mean of its divisors is an integer number (110689641).

Almost surely, 2^221379281 is an apocalyptic number.

It is an amenable number.

221379281 is a deficient number, since it is larger than the sum of its proper divisors (1).

221379281 is an equidigital number, since it uses as much as digits as its factorization.

221379281 is an evil number, because the sum of its binary digits is even.

The product of its digits is 12096, while the sum is 35.

The square root of 221379281 is about 14878.8198792781. The cubic root of 221379281 is about 604.9400309386.

The spelling of 221379281 in words is "two hundred twenty-one million, three hundred seventy-nine thousand, two hundred eighty-one".