221131997 has 2 divisors, whose sum is σ = 221131998. Its totient is φ = 221131996.

The previous prime is 221131991. The next prime is 221132029. The reversal of 221131997 is 799131122.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 183358681 + 37773316 = 13541^2 + 6146^2 .

It is a cyclic number.

It is not a de Polignac number, because 221131997 - 2¹² = 221127901 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (221131991) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 110565998 + 110565999.

It is an arithmetic number, because the mean of its divisors is an integer number (110565999).

Almost surely, 2^221131997 is an apocalyptic number.

It is an amenable number.

221131997 is a deficient number, since it is larger than the sum of its proper divisors (1).

221131997 is an equidigital number, since it uses as much as digits as its factorization.

221131997 is an evil number, because the sum of its binary digits is even.

The product of its digits is 6804, while the sum is 35.

The square root of 221131997 is about 14870.5076241533. The cubic root of 221131997 is about 604.7147046369.

The spelling of 221131997 in words is "two hundred twenty-one million, one hundred thirty-one thousand, nine hundred ninety-seven".