1780421 has 4 divisors (see below), whose sum is σ = 1794144. Its totient is φ = 1766700.

The previous prime is 1780411. The next prime is 1780439. The reversal of 1780421 is 1240871.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 1240871 = 19 ⋅65309.

It is a cyclic number.

It is not a de Polignac number, because 1780421 - 2¹⁸ = 1518277 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 (1780411) 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 3 ways as a sum of consecutive naturals, for example, 6665 + ... + 6926.

It is an arithmetic number, because the mean of its divisors is an integer number (448536).

2^1780421 is an apocalyptic number.

It is an amenable number.

1780421 is a deficient number, since it is larger than the sum of its proper divisors (13723).

1780421 is a wasteful number, since it uses less digits than its factorization.

1780421 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 13722.

The product of its (nonzero) digits is 448, while the sum is 23.

The square root of 1780421 is about 1334.3241735051. The cubic root of 1780421 is about 121.2013812940.

The spelling of 1780421 in words is "one million, seven hundred eighty thousand, four hundred twenty-one".