221666051 has 2 divisors, whose sum is σ = 221666052. Its totient is φ = 221666050.

The previous prime is 221666041. The next prime is 221666057. The reversal of 221666051 is 150666122.

221666051 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 221666051 - 2⁶ = 221665987 is a prime.

It is equal to p_12209186 and since 221666051 and 12209186 have the same sum of digits, it is a Honaker prime.

It is not a weakly prime, because it can be changed into another prime (221666057) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 110833025 + 110833026.

It is an arithmetic number, because the mean of its divisors is an integer number (110833026).

Almost surely, 2^221666051 is an apocalyptic number.

221666051 is a deficient number, since it is larger than the sum of its proper divisors (1).

221666051 is an equidigital number, since it uses as much as digits as its factorization.

221666051 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 4320, while the sum is 29.

The square root of 221666051 is about 14888.4536134550. The cubic root of 221666051 is about 605.2011270372.

The spelling of 221666051 in words is "two hundred twenty-one million, six hundred sixty-six thousand, fifty-one".