1561851 has 6 divisors (see below), whose sum is σ = 2256020. Its totient is φ = 1041228.

The previous prime is 1561829. The next prime is 1561883. The reversal of 1561851 is 1581651.

It is not a de Polignac number, because 1561851 - 2¹⁹ = 1037563 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1561801) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 86761 + ... + 86778.

2^1561851 is an apocalyptic number.

1561851 is a deficient number, since it is larger than the sum of its proper divisors (694169).

1561851 is a wasteful number, since it uses less digits than its factorization.

1561851 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 173545 (or 173542 counting only the distinct ones).

The product of its digits is 1200, while the sum is 27.

The square root of 1561851 is about 1249.7403730375. The cubic root of 1561851 is about 116.0236525293.

Subtracting from 1561851 its product of digits (1200), we obtain a palindrome (1560651).

The spelling of 1561851 in words is "one million, five hundred sixty-one thousand, eight hundred fifty-one".