1640990 has 24 divisors (see below), whose sum is σ = 3201768. Its totient is φ = 605280.

The previous prime is 1640971. The next prime is 1641007. The reversal of 1640990 is 990461.

It is a Curzon number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 1205 + ... + 2175.

It is an arithmetic number, because the mean of its divisors is an integer number (133407).

2^1640990 is an apocalyptic number.

1640990 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

1640990 is a deficient number, since it is larger than the sum of its proper divisors (1560778).

1640990 is a wasteful number, since it uses less digits than its factorization.

1640990 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1004 (or 991 counting only the distinct ones).

The product of its (nonzero) digits is 1944, while the sum is 29.

The square root of 1640990 is about 1281.0113192318. The cubic root of 1640990 is about 117.9510953142.

Subtracting from 1640990 its sum of digits (29), we obtain a square (1640961 = 1281²).

The spelling of 1640990 in words is "one million, six hundred forty thousand, nine hundred ninety".