221551081 has 2 divisors, whose sum is σ = 221551082. Its totient is φ = 221551080.

The previous prime is 221551063. The next prime is 221551087. The reversal of 221551081 is 180155122.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 183358681 + 38192400 = 13541^2 + 6180^2 .

It is a cyclic number.

It is not a de Polignac number, because 221551081 - 2¹³ = 221542889 is a prime.

It is a super-2 number, since 2×221551081² = 98169762984537122, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (221551087) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 110775540 + 110775541.

It is an arithmetic number, because the mean of its divisors is an integer number (110775541).

Almost surely, 2^221551081 is an apocalyptic number.

It is an amenable number.

221551081 is a deficient number, since it is larger than the sum of its proper divisors (1).

221551081 is an equidigital number, since it uses as much as digits as its factorization.

221551081 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 800, while the sum is 25.

The square root of 221551081 is about 14884.5920669664. The cubic root of 221551081 is about 605.0964771126.

The spelling of 221551081 in words is "two hundred twenty-one million, five hundred fifty-one thousand, eighty-one".