1664651 has 2 divisors, whose sum is σ = 1664652. Its totient is φ = 1664650.

The previous prime is 1664633. The next prime is 1664653. The reversal of 1664651 is 1564661.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1664651 is a prime.

It is a Sophie Germain prime.

Together with 1664653, 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 (1664653) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 832325 + 832326.

It is an arithmetic number, because the mean of its divisors is an integer number (832326).

2^1664651 is an apocalyptic number.

1664651 is a deficient number, since it is larger than the sum of its proper divisors (1).

1664651 is an equidigital number, since it uses as much as digits as its factorization.

1664651 is an odious number, because the sum of its binary digits is odd.

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

The square root of 1664651 is about 1290.2135482160. The cubic root of 1664651 is about 118.5152941264.

The spelling of 1664651 in words is "one million, six hundred sixty-four thousand, six hundred fifty-one".