1666985057 has 2 divisors, whose sum is σ = 1666985058. Its totient is φ = 1666985056.

The previous prime is 1666985051. The next prime is 1666985059. The reversal of 1666985057 is 7505896661.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 1282785856 + 384199201 = 35816^2 + 19601^2 .

It is a cyclic number.

It is not a de Polignac number, because 1666985057 - 2¹² = 1666980961 is a prime.

It is a super-2 number, since 2×1666985057² = 5557678360522586498, which contains 22 as substring.

Together with 1666985059, 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 (1666985051) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 833492528 + 833492529.

It is an arithmetic number, because the mean of its divisors is an integer number (833492529).

Almost surely, 2^1666985057 is an apocalyptic number.

It is an amenable number.

1666985057 is a deficient number, since it is larger than the sum of its proper divisors (1).

1666985057 is an equidigital number, since it uses as much as digits as its factorization.

1666985057 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 2721600, while the sum is 53.

The square root of 1666985057 is about 40828.7283294496. The cubic root of 1666985057 is about 1185.7065953859.

The spelling of 1666985057 in words is "one billion, six hundred sixty-six million, nine hundred eighty-five thousand, fifty-seven".