1643623 has 2 divisors, whose sum is σ = 1643624. Its totient is φ = 1643622.

The previous prime is 1643617. The next prime is 1643639. The reversal of 1643623 is 3263461.

It is a weak prime.

It is an emirp because it is prime and its reverse (3263461) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 1643623 - 2⁵ = 1643591 is a prime.

It is a super-2 number, since 2×1643623² = 5402993132258, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1643683) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 821811 + 821812.

It is an arithmetic number, because the mean of its divisors is an integer number (821812).

2^1643623 is an apocalyptic number.

1643623 is a deficient number, since it is larger than the sum of its proper divisors (1).

1643623 is an equidigital number, since it uses as much as digits as its factorization.

1643623 is an evil number, because the sum of its binary digits is even.

The product of its digits is 2592, while the sum is 25.

The square root of 1643623 is about 1282.0386109630. The cubic root of 1643623 is about 118.0141465372.

The spelling of 1643623 in words is "one million, six hundred forty-three thousand, six hundred twenty-three".