1551643 has 4 divisors (see below), whose sum is σ = 1601728. Its totient is φ = 1501560.

The previous prime is 1551623. The next prime is 1551647. The reversal of 1551643 is 3461551.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1551643 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1551647) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 24996 + ... + 25057.

It is an arithmetic number, because the mean of its divisors is an integer number (400432).

2^1551643 is an apocalyptic number.

1551643 is a deficient number, since it is larger than the sum of its proper divisors (50085).

1551643 is an equidigital number, since it uses as much as digits as its factorization.

1551643 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 50084.

The product of its digits is 1800, while the sum is 25.

The square root of 1551643 is about 1245.6496297113. The cubic root of 1551643 is about 115.7703293599.

The spelling of 1551643 in words is "one million, five hundred fifty-one thousand, six hundred forty-three".