221291923 has 2 divisors, whose sum is σ = 221291924. Its totient is φ = 221291922.

The previous prime is 221291899. The next prime is 221291927. The reversal of 221291923 is 329192122.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 221291923 - 2¹³ = 221283731 is a prime.

It is not a weakly prime, because it can be changed into another prime (221291927) 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, 110645961 + 110645962.

It is an arithmetic number, because the mean of its divisors is an integer number (110645962).

Almost surely, 2^221291923 is an apocalyptic number.

221291923 is a deficient number, since it is larger than the sum of its proper divisors (1).

221291923 is an equidigital number, since it uses as much as digits as its factorization.

221291923 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 3888, while the sum is 31.

The square root of 221291923 is about 14875.8839401227. The cubic root of 221291923 is about 604.8604491101.

The spelling of 221291923 in words is "two hundred twenty-one million, two hundred ninety-one thousand, nine hundred twenty-three".