1640664 has 24 divisors (see below), whose sum is σ = 4443660. Its totient is φ = 546864.

The previous prime is 1640663. The next prime is 1640677. The reversal of 1640664 is 4660461.

It is a tau number, because it is divible by the number of its divisors (24).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1640663) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 11322 + ... + 11465.

2^1640664 is an apocalyptic number.

It is an amenable number.

1640664 is an abundant number, since it is smaller than the sum of its proper divisors (2802996).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

1640664 is a wasteful number, since it uses less digits than its factorization.

1640664 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 22799 (or 22792 counting only the distinct ones).

The product of its (nonzero) digits is 3456, while the sum is 27.

The square root of 1640664 is about 1280.8840696956. The cubic root of 1640664 is about 117.9432840532.

It can be divided in two parts, 1640 and 664, that added together give a square (2304 = 48²).

The spelling of 1640664 in words is "one million, six hundred forty thousand, six hundred sixty-four".