1780121 has 12 divisors (see below), whose sum is σ = 2193588. Its totient is φ = 1435392.

The previous prime is 1780099. The next prime is 1780127. The reversal of 1780121 is 1210871.

It can be written as a sum of positive squares in 2 ways, for example, as 648025 + 1132096 = 805^2 + 1064^2 .

It is not a de Polignac number, because 1780121 - 2¹⁰ = 1779097 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 1780093 and 1780102.

It is not an unprimeable number, because it can be changed into a prime (1780127) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 236 + ... + 1901.

It is an arithmetic number, because the mean of its divisors is an integer number (182799).

2^1780121 is an apocalyptic number.

It is an amenable number.

1780121 is a deficient number, since it is larger than the sum of its proper divisors (413467).

1780121 is a wasteful number, since it uses less digits than its factorization.

1780121 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2168 (or 2161 counting only the distinct ones).

The product of its (nonzero) digits is 112, while the sum is 20.

The square root of 1780121 is about 1334.2117523092. The cubic root of 1780121 is about 121.1945734553.

Adding to 1780121 its reverse (1210871), we get a palindrome (2990992).

The spelling of 1780121 in words is "one million, seven hundred eighty thousand, one hundred twenty-one".