1664425791 has 24 divisors (see below), whose sum is σ = 2814643104. Its totient is φ = 927901440.

The previous prime is 1664425787. The next prime is 1664425793. The reversal of 1664425791 is 1975244661.

1664425791 is a `hidden beast` number, since 16 + 64 + 4 + 2 + 579 + 1 = 666.

It is not a de Polignac number, because 1664425791 - 2² = 1664425787 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1664425793) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 319606 + ... + 324771.

It is an arithmetic number, because the mean of its divisors is an integer number (117276796).

Almost surely, 2^1664425791 is an apocalyptic number.

1664425791 is a deficient number, since it is larger than the sum of its proper divisors (1150217313).

1664425791 is a wasteful number, since it uses less digits than its factorization.

1664425791 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 644431 (or 644428 counting only the distinct ones).

The product of its digits is 362880, while the sum is 45.

The square root of 1664425791 is about 40797.3748052494. The cubic root of 1664425791 is about 1185.0994927947.

The spelling of 1664425791 in words is "one billion, six hundred sixty-four million, four hundred twenty-five thousand, seven hundred ninety-one".