221220997 has 2 divisors, whose sum is σ = 221220998. Its totient is φ = 221220996.

The previous prime is 221220973. The next prime is 221221037. The reversal of 221220997 is 799022122.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 136562596 + 84658401 = 11686^2 + 9201^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-221220997 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (221220907) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 110610498 + 110610499.

It is an arithmetic number, because the mean of its divisors is an integer number (110610499).

Almost surely, 2^221220997 is an apocalyptic number.

It is an amenable number.

221220997 is a deficient number, since it is larger than the sum of its proper divisors (1).

221220997 is an equidigital number, since it uses as much as digits as its factorization.

221220997 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 9072, while the sum is 34.

The square root of 221220997 is about 14873.4998235116. The cubic root of 221220997 is about 604.7958211807.

The spelling of 221220997 in words is "two hundred twenty-one million, two hundred twenty thousand, nine hundred ninety-seven".