1666215667 has 2 divisors, whose sum is σ = 1666215668. Its totient is φ = 1666215666.

The previous prime is 1666215631. The next prime is 1666215689. The reversal of 1666215667 is 7665126661.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1666215667 is a prime.

It is not a weakly prime, because it can be changed into another prime (1666215167) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 833107833 + 833107834.

It is an arithmetic number, because the mean of its divisors is an integer number (833107834).

Almost surely, 2^1666215667 is an apocalyptic number.

1666215667 is a deficient number, since it is larger than the sum of its proper divisors (1).

1666215667 is an equidigital number, since it uses as much as digits as its factorization.

1666215667 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 544320, while the sum is 46.

The square root of 1666215667 is about 40819.3050773773. The cubic root of 1666215667 is about 1185.5241480026.

The spelling of 1666215667 in words is "one billion, six hundred sixty-six million, two hundred fifteen thousand, six hundred sixty-seven".