243977221997 has 2 divisors, whose sum is σ = 243977221998. Its totient is φ = 243977221996.

The previous prime is 243977221973. The next prime is 243977222059. The reversal of 243977221997 is 799122779342.

It is an a-pointer prime, because the next prime (243977222059) can be obtained adding 243977221997 to its sum of digits (62).

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 191306512996 + 52670709001 = 437386^2 + 229501^2 .

It is a cyclic number.

It is not a de Polignac number, because 243977221997 - 2²² = 243973027693 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (243977221297) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 121988610998 + 121988610999.

It is an arithmetic number, because the mean of its divisors is an integer number (121988610999).

Almost surely, 2^243977221997 is an apocalyptic number.

It is an amenable number.

243977221997 is a deficient number, since it is larger than the sum of its proper divisors (1).

243977221997 is an equidigital number, since it uses as much as digits as its factorization.

243977221997 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 24004512, while the sum is 62.

The spelling of 243977221997 in words is "two hundred forty-three billion, nine hundred seventy-seven million, two hundred twenty-one thousand, nine hundred ninety-seven".