221665427 has 2 divisors, whose sum is σ = 221665428. Its totient is φ = 221665426.

The previous prime is 221665369. The next prime is 221665429. The reversal of 221665427 is 724566122.

221665427 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 221665427 - 2¹⁸ = 221403283 is a prime.

Together with 221665429, it forms a pair of twin primes.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (221665429) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 110832713 + 110832714.

It is an arithmetic number, because the mean of its divisors is an integer number (110832714).

Almost surely, 2^221665427 is an apocalyptic number.

221665427 is a deficient number, since it is larger than the sum of its proper divisors (1).

221665427 is an equidigital number, since it uses as much as digits as its factorization.

221665427 is an evil number, because the sum of its binary digits is even.

The product of its digits is 40320, while the sum is 35.

The square root of 221665427 is about 14888.4326576037. The cubic root of 221665427 is about 605.2005591471.

The spelling of 221665427 in words is "two hundred twenty-one million, six hundred sixty-five thousand, four hundred twenty-seven".