664561111 has 2 divisors, whose sum is σ = 664561112. Its totient is φ = 664561110.

The previous prime is 664561109. The next prime is 664561133. The reversal of 664561111 is 111165466.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 664561111 - 2¹ = 664561109 is a prime.

Together with 664561109, it forms a pair of twin primes.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (664561151) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 332280555 + 332280556.

It is an arithmetic number, because the mean of its divisors is an integer number (332280556).

Almost surely, 2^664561111 is an apocalyptic number.

664561111 is a deficient number, since it is larger than the sum of its proper divisors (1).

664561111 is an equidigital number, since it uses as much as digits as its factorization.

664561111 is an evil number, because the sum of its binary digits is even.

The product of its digits is 4320, while the sum is 31.

The square root of 664561111 is about 25779.0828192160. The cubic root of 664561111 is about 872.6598086597.

The spelling of 664561111 in words is "six hundred sixty-four million, five hundred sixty-one thousand, one hundred eleven".