1851649 has 2 divisors, whose sum is σ = 1851650. Its totient is φ = 1851648.

The previous prime is 1851643. The next prime is 1851667. The reversal of 1851649 is 9461581.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1299600 + 552049 = 1140^2 + 743^2 .

It is an emirp because it is prime and its reverse (9461581) is a distict prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1851649 is a prime.

It is not a weakly prime, because it can be changed into another prime (1851643) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 925824 + 925825.

It is an arithmetic number, because the mean of its divisors is an integer number (925825).

2^1851649 is an apocalyptic number.

It is an amenable number.

1851649 is a deficient number, since it is larger than the sum of its proper divisors (1).

1851649 is an equidigital number, since it uses as much as digits as its factorization.

1851649 is an evil number, because the sum of its binary digits is even.

The product of its digits is 8640, while the sum is 34.

The square root of 1851649 is about 1360.7531003088. The cubic root of 1851649 is about 122.7965659153.

It can be divided in two parts, 1851 and 649, that added together give a square (2500 = 50²).

The spelling of 1851649 in words is "one million, eight hundred fifty-one thousand, six hundred forty-nine".