1279921 has 2 divisors, whose sum is σ = 1279922. Its totient is φ = 1279920.

The previous prime is 1279919. The next prime is 1279931. The reversal of 1279921 is 1299721.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 774400 + 505521 = 880^2 + 711^2 .

It is an emirp because it is prime and its reverse (1299721) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 1279921 - 2¹ = 1279919 is a prime.

Together with 1279919, it forms a pair of twin primes.

It is a Chen prime.

1279921 is a lucky number.

It is not a weakly prime, because it can be changed into another prime (1279931) 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 as a sum of consecutive naturals, namely, 639960 + 639961.

It is an arithmetic number, because the mean of its divisors is an integer number (639961).

2^1279921 is an apocalyptic number.

It is an amenable number.

1279921 is a deficient number, since it is larger than the sum of its proper divisors (1).

1279921 is an equidigital number, since it uses as much as digits as its factorization.

1279921 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 2268, while the sum is 31.

The square root of 1279921 is about 1131.3359359624. The cubic root of 1279921 is about 108.5744708783.

The spelling of 1279921 in words is "one million, two hundred seventy-nine thousand, nine hundred twenty-one".