1640644 has 24 divisors (see below), whose sum is σ = 3015936. Its totient is φ = 780000.

The previous prime is 1640641. The next prime is 1640657. The reversal of 1640644 is 4460461.

It is not an unprimeable number, because it can be changed into a prime (1640641) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 12459 + ... + 12589.

It is an arithmetic number, because the mean of its divisors is an integer number (125664).

2^1640644 is an apocalyptic number.

It is an amenable number.

1640644 is a deficient number, since it is larger than the sum of its proper divisors (1375292).

1640644 is a wasteful number, since it uses less digits than its factorization.

1640644 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 267 (or 265 counting only the distinct ones).

The product of its (nonzero) digits is 2304, while the sum is 25.

The square root of 1640644 is about 1280.8762625640. The cubic root of 1640644 is about 117.9428048011.

The spelling of 1640644 in words is "one million, six hundred forty thousand, six hundred forty-four".