221891897 has 2 divisors, whose sum is σ = 221891898. Its totient is φ = 221891896.

The previous prime is 221891851. The next prime is 221891909. The reversal of 221891897 is 798198122.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 203091001 + 18800896 = 14251^2 + 4336^2 .

It is a cyclic number.

It is not a de Polignac number, because 221891897 - 2²⁴ = 205114681 is a prime.

It is not a weakly prime, because it can be changed into another prime (221891807) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 110945948 + 110945949.

It is an arithmetic number, because the mean of its divisors is an integer number (110945949).

Almost surely, 2^221891897 is an apocalyptic number.

It is an amenable number.

221891897 is a deficient number, since it is larger than the sum of its proper divisors (1).

221891897 is an equidigital number, since it uses as much as digits as its factorization.

221891897 is an evil number, because the sum of its binary digits is even.

The product of its digits is 145152, while the sum is 47.

The square root of 221891897 is about 14896.0362848645. The cubic root of 221891897 is about 605.4065950666.

The spelling of 221891897 in words is "two hundred twenty-one million, eight hundred ninety-one thousand, eight hundred ninety-seven".