1640380385 has 32 divisors (see below), whose sum is σ = 2318464512. Its totient is φ = 1090644480.

The previous prime is 1640380381. The next prime is 1640380421. The reversal of 1640380385 is 5830830461.

It is not a de Polignac number, because 1640380385 - 2² = 1640380381 is a prime.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (1640380381) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 400709 + ... + 404781.

It is an arithmetic number, because the mean of its divisors is an integer number (72452016).

Almost surely, 2^1640380385 is an apocalyptic number.

It is an amenable number.

1640380385 is a deficient number, since it is larger than the sum of its proper divisors (678084127).

1640380385 is a wasteful number, since it uses less digits than its factorization.

1640380385 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4433.

The product of its (nonzero) digits is 69120, while the sum is 38.

The square root of 1640380385 is about 40501.6096593703. The cubic root of 1640380385 is about 1179.3648753421.

The spelling of 1640380385 in words is "one billion, six hundred forty million, three hundred eighty thousand, three hundred eighty-five".