1640663 has 2 divisors, whose sum is σ = 1640664. Its totient is φ = 1640662.

The previous prime is 1640657. The next prime is 1640677. The reversal of 1640663 is 3660461.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 1640663 - 2⁶ = 1640599 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1640623) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 820331 + 820332.

It is an arithmetic number, because the mean of its divisors is an integer number (820332).

2^1640663 is an apocalyptic number.

1640663 is a deficient number, since it is larger than the sum of its proper divisors (1).

1640663 is an equidigital number, since it uses as much as digits as its factorization.

1640663 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 2592, while the sum is 26.

The square root of 1640663 is about 1280.8836793402. The cubic root of 1640663 is about 117.9432600907.

The spelling of 1640663 in words is "one million, six hundred forty thousand, six hundred sixty-three".