1640165623 has 4 divisors (see below), whose sum is σ = 1643723928. Its totient is φ = 1636607320.

The previous prime is 1640165609. The next prime is 1640165651. The reversal of 1640165623 is 3265610461.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 1640165623 - 2²⁹ = 1103294711 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1640165663) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1778461 + ... + 1779382.

It is an arithmetic number, because the mean of its divisors is an integer number (410930982).

Almost surely, 2^1640165623 is an apocalyptic number.

1640165623 is a deficient number, since it is larger than the sum of its proper divisors (3558305).

1640165623 is an equidigital number, since it uses as much as digits as its factorization.

1640165623 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3558304.

The product of its (nonzero) digits is 25920, while the sum is 34.

The square root of 1640165623 is about 40498.9582952451. The cubic root of 1640165623 is about 1179.3134047979.

The spelling of 1640165623 in words is "one billion, six hundred forty million, one hundred sixty-five thousand, six hundred twenty-three".