1664445457 has 2 divisors, whose sum is σ = 1664445458. Its totient is φ = 1664445456.

The previous prime is 1664445449. The next prime is 1664445491. The reversal of 1664445457 is 7545444661.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1381162896 + 283282561 = 37164^2 + 16831^2 .

It is an emirp because it is prime and its reverse (7545444661) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 1664445457 - 2³ = 1664445449 is a prime.

It is not a weakly prime, because it can be changed into another prime (1664445157) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 832222728 + 832222729.

It is an arithmetic number, because the mean of its divisors is an integer number (832222729).

Almost surely, 2^1664445457 is an apocalyptic number.

It is an amenable number.

1664445457 is a deficient number, since it is larger than the sum of its proper divisors (1).

1664445457 is an equidigital number, since it uses as much as digits as its factorization.

1664445457 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1612800, while the sum is 46.

The square root of 1664445457 is about 40797.6158249474. The cubic root of 1664445457 is about 1185.1041602852.

The spelling of 1664445457 in words is "one billion, six hundred sixty-four million, four hundred forty-five thousand, four hundred fifty-seven".