1640661 has 16 divisors (see below), whose sum is σ = 2419200. Its totient is φ = 980720.

The previous prime is 1640657. The next prime is 1640663. The reversal of 1640661 is 1660461.

It is a cyclic number.

It is not a de Polignac number, because 1640661 - 2² = 1640657 is a prime.

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 15 ways as a sum of consecutive naturals, for example, 2440 + ... + 3038.

It is an arithmetic number, because the mean of its divisors is an integer number (151200).

2^1640661 is an apocalyptic number.

1640661 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

It is an amenable number.

1640661 is a deficient number, since it is larger than the sum of its proper divisors (778539).

1640661 is a wasteful number, since it uses less digits than its factorization.

1640661 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 696.

The product of its (nonzero) digits is 864, while the sum is 24.

The square root of 1640661 is about 1280.8828986289. The cubic root of 1640661 is about 117.9432121656.

The spelling of 1640661 in words is "one million, six hundred forty thousand, six hundred sixty-one".