221529991 has 2 divisors, whose sum is σ = 221529992. Its totient is φ = 221529990.

The previous prime is 221529953. The next prime is 221530019. The reversal of 221529991 is 199925122.

221529991 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 221529991 - 2⁹ = 221529479 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (221529901) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 110764995 + 110764996.

It is an arithmetic number, because the mean of its divisors is an integer number (110764996).

Almost surely, 2^221529991 is an apocalyptic number.

221529991 is a deficient number, since it is larger than the sum of its proper divisors (1).

221529991 is an equidigital number, since it uses as much as digits as its factorization.

221529991 is an evil number, because the sum of its binary digits is even.

The product of its digits is 29160, while the sum is 40.

The square root of 221529991 is about 14883.8835993836. The cubic root of 221529991 is about 605.0772762890.

The spelling of 221529991 in words is "two hundred twenty-one million, five hundred twenty-nine thousand, nine hundred ninety-one".