1665606947 has 2 divisors, whose sum is σ = 1665606948. Its totient is φ = 1665606946.

The previous prime is 1665606941. The next prime is 1665606949. The reversal of 1665606947 is 7496065661.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 1665606947 - 2⁶ = 1665606883 is a prime.

Together with 1665606949, it forms a pair of twin primes.

It is a Chen prime.

It is a junction number, because it is equal to n+sod(n) for n = 1665606895 and 1665606904.

It is not a weakly prime, because it can be changed into another prime (1665606941) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 832803473 + 832803474.

It is an arithmetic number, because the mean of its divisors is an integer number (832803474).

Almost surely, 2^1665606947 is an apocalyptic number.

1665606947 is a deficient number, since it is larger than the sum of its proper divisors (1).

1665606947 is an equidigital number, since it uses as much as digits as its factorization.

1665606947 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1632960, while the sum is 50.

The square root of 1665606947 is about 40811.8481203682. The cubic root of 1665606947 is about 1185.3797608999.

The spelling of 1665606947 in words is "one billion, six hundred sixty-five million, six hundred six thousand, nine hundred forty-seven".