1851661 has 24 divisors (see below), whose sum is σ = 2363904. Its totient is φ = 1441440.

The previous prime is 1851649. The next prime is 1851667. The reversal of 1851661 is 1661581.

1851661 is nontrivially palindromic in base 6.

It is not a de Polignac number, because 1851661 - 2¹⁹ = 1327373 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1851667) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 34911 + ... + 34963.

It is an arithmetic number, because the mean of its divisors is an integer number (98496).

2^1851661 is an apocalyptic number.

It is an amenable number.

1851661 is a deficient number, since it is larger than the sum of its proper divisors (512243).

1851661 is a wasteful number, since it uses less digits than its factorization.

1851661 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 121 (or 114 counting only the distinct ones).

The product of its digits is 1440, while the sum is 28.

The square root of 1851661 is about 1360.7575096247. The cubic root of 1851661 is about 122.7968311843.

The spelling of 1851661 in words is "one million, eight hundred fifty-one thousand, six hundred sixty-one".