221397923 has 2 divisors, whose sum is σ = 221397924. Its totient is φ = 221397922.

The previous prime is 221397893. The next prime is 221397947. The reversal of 221397923 is 329793122.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 221397923 - 2¹⁴ = 221381539 is a prime.

It is not a weakly prime, because it can be changed into another prime (221397983) 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, 110698961 + 110698962.

It is an arithmetic number, because the mean of its divisors is an integer number (110698962).

Almost surely, 2^221397923 is an apocalyptic number.

221397923 is a deficient number, since it is larger than the sum of its proper divisors (1).

221397923 is an equidigital number, since it uses as much as digits as its factorization.

221397923 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 40824, while the sum is 38.

The square root of 221397923 is about 14879.4463270647. The cubic root of 221397923 is about 604.9570108106.

The spelling of 221397923 in words is "two hundred twenty-one million, three hundred ninety-seven thousand, nine hundred twenty-three".