1605551 has 2 divisors, whose sum is σ = 1605552. Its totient is φ = 1605550.

The previous prime is 1605547. The next prime is 1605553. The reversal of 1605551 is 1555061.

It is a strong prime.

It is an emirp because it is prime and its reverse (1555061) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 1605551 - 2² = 1605547 is a prime.

Together with 1605553, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1605553) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 802775 + 802776.

It is an arithmetic number, because the mean of its divisors is an integer number (802776).

2^1605551 is an apocalyptic number.

1605551 is a deficient number, since it is larger than the sum of its proper divisors (1).

1605551 is an equidigital number, since it uses as much as digits as its factorization.

1605551 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 750, while the sum is 23.

The square root of 1605551 is about 1267.1033896253. The cubic root of 1605551 is about 117.0958135937.

The spelling of 1605551 in words is "one million, six hundred five thousand, five hundred fifty-one".