1278021 has 4 divisors (see below), whose sum is σ = 1704032. Its totient is φ = 852012.

The previous prime is 1278007. The next prime is 1278029. The reversal of 1278021 is 1208721.

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.

It is not a de Polignac number, because 1278021 - 2⁶ = 1277957 is a prime.

It is a D-number.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1278029) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 213001 + ... + 213006.

It is an arithmetic number, because the mean of its divisors is an integer number (426008).

2^1278021 is an apocalyptic number.

It is an amenable number.

1278021 is a deficient number, since it is larger than the sum of its proper divisors (426011).

1278021 is an equidigital number, since it uses as much as digits as its factorization.

1278021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 426010.

The product of its (nonzero) digits is 224, while the sum is 21.

The square root of 1278021 is about 1130.4959088825. The cubic root of 1278021 is about 108.5207192128.

The spelling of 1278021 in words is "one million, two hundred seventy-eight thousand, twenty-one".