1645643 has 2 divisors, whose sum is σ = 1645644. Its totient is φ = 1645642.

The previous prime is 1645613. The next prime is 1645661. The reversal of 1645643 is 3465461.

It is a happy number.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 1645643 - 2¹⁴ = 1629259 is a prime.

It is not a weakly prime, because it can be changed into another prime (1645603) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 822821 + 822822.

It is an arithmetic number, because the mean of its divisors is an integer number (822822).

2^1645643 is an apocalyptic number.

1645643 is a deficient number, since it is larger than the sum of its proper divisors (1).

1645643 is an equidigital number, since it uses as much as digits as its factorization.

1645643 is an evil number, because the sum of its binary digits is even.

The product of its digits is 8640, while the sum is 29.

The square root of 1645643 is about 1282.8261768455. The cubic root of 1645643 is about 118.0624729039.

The spelling of 1645643 in words is "one million, six hundred forty-five thousand, six hundred forty-three".