1640404 has 12 divisors (see below), whose sum is σ = 2880724. Its totient is φ = 817344.

The previous prime is 1640399. The next prime is 1640423. The reversal of 1640404 is 4040461.

It can be written as a sum of positive squares in 2 ways, for example, as 1392400 + 248004 = 1180^2 + 498^2 .

1640404 is a modest number, since divided by 404 gives 164 as remainder.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1072 + ... + 2104.

2^1640404 is an apocalyptic number.

It is an amenable number.

1640404 is a deficient number, since it is larger than the sum of its proper divisors (1240320).

1640404 is a wasteful number, since it uses less digits than its factorization.

1640404 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1434 (or 1432 counting only the distinct ones).

The product of its (nonzero) digits is 384, while the sum is 19.

The square root of 1640404 is about 1280.7825732731. The cubic root of 1640404 is about 117.9370534714.

Adding to 1640404 its reverse (4040461), we get a palindrome (5680865).

The spelling of 1640404 in words is "one million, six hundred forty thousand, four hundred four".