1640647 has 4 divisors (see below), whose sum is σ = 1655280. Its totient is φ = 1626016.

The previous prime is 1640641. The next prime is 1640657. The reversal of 1640647 is 7460461.

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 1640647 - 2⁷ = 1640519 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 (1640641) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 7147 + ... + 7372.

It is an arithmetic number, because the mean of its divisors is an integer number (413820).

2^1640647 is an apocalyptic number.

1640647 is a deficient number, since it is larger than the sum of its proper divisors (14633).

1640647 is a wasteful number, since it uses less digits than its factorization.

1640647 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 14632.

The product of its (nonzero) digits is 4032, while the sum is 28.

The square root of 1640647 is about 1280.8774336368. The cubic root of 1640647 is about 117.9428766891.

The spelling of 1640647 in words is "one million, six hundred forty thousand, six hundred forty-seven".