221770780981 has 2 divisors, whose sum is σ = 221770780982. Its totient is φ = 221770780980.

The previous prime is 221770780939. The next prime is 221770781021. The reversal of 221770780981 is 189087077122.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 220125180625 + 1645600356 = 469175^2 + 40566^2 .

It is a cyclic number.

It is not a de Polignac number, because 221770780981 - 2⁷ = 221770780853 is a prime.

It is a super-2 number, since 2×221770780981² (a number of 23 digits) contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (221770780181) 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 as a sum of consecutive naturals, namely, 110885390490 + 110885390491.

It is an arithmetic number, because the mean of its divisors is an integer number (110885390491).

Almost surely, 2^221770780981 is an apocalyptic number.

It is an amenable number.

221770780981 is a deficient number, since it is larger than the sum of its proper divisors (1).

221770780981 is an equidigital number, since it uses as much as digits as its factorization.

221770780981 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 790272, while the sum is 52.

The spelling of 221770780981 in words is "two hundred twenty-one billion, seven hundred seventy million, seven hundred eighty thousand, nine hundred eighty-one".