1555643 has 2 divisors, whose sum is σ = 1555644. Its totient is φ = 1555642.

The previous prime is 1555639. The next prime is 1555657. The reversal of 1555643 is 3465551.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 1555643 - 2² = 1555639 is a prime.

It is a Sophie Germain prime.

It is not a weakly prime, because it can be changed into another prime (1555613) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 777821 + 777822.

It is an arithmetic number, because the mean of its divisors is an integer number (777822).

2^1555643 is an apocalyptic number.

1555643 is a deficient number, since it is larger than the sum of its proper divisors (1).

1555643 is an equidigital number, since it uses as much as digits as its factorization.

1555643 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 9000, while the sum is 29.

The square root of 1555643 is about 1247.2541841982. The cubic root of 1555643 is about 115.8697259261.

The spelling of 1555643 in words is "one million, five hundred fifty-five thousand, six hundred forty-three".