221439997 has 2 divisors, whose sum is σ = 221439998. Its totient is φ = 221439996.

The previous prime is 221439979. The next prime is 221440007. The reversal of 221439997 is 799934122.

It is a happy number.

Together with previous prime (221439979) it forms an Ormiston pair, because they use the same digits, order apart.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 221087161 + 352836 = 14869^2 + 594^2 .

It is a cyclic number.

It is not a de Polignac number, because 221439997 - 2²⁷ = 87222269 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (221439917) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 110719998 + 110719999.

It is an arithmetic number, because the mean of its divisors is an integer number (110719999).

Almost surely, 2^221439997 is an apocalyptic number.

It is an amenable number.

221439997 is a deficient number, since it is larger than the sum of its proper divisors (1).

221439997 is an equidigital number, since it uses as much as digits as its factorization.

221439997 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 244944, while the sum is 46.

The square root of 221439997 is about 14880.8600893900. The cubic root of 221439997 is about 604.9953299733.

The spelling of 221439997 in words is "two hundred twenty-one million, four hundred thirty-nine thousand, nine hundred ninety-seven".