1188721 has 2 divisors, whose sum is σ = 1188722. Its totient is φ = 1188720.

The previous prime is 1188689. The next prime is 1188727. The reversal of 1188721 is 1278811.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 746496 + 442225 = 864^2 + 665^2 .

It is an emirp because it is prime and its reverse (1278811) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 1188721 - 2⁵ = 1188689 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 1188721.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1188727) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 594360 + 594361.

It is an arithmetic number, because the mean of its divisors is an integer number (594361).

2^1188721 is an apocalyptic number.

It is an amenable number.

1188721 is a deficient number, since it is larger than the sum of its proper divisors (1).

1188721 is an equidigital number, since it uses as much as digits as its factorization.

1188721 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 896, while the sum is 28.

The square root of 1188721 is about 1090.2848251718. The cubic root of 1188721 is about 105.9318714940.

The spelling of 1188721 in words is "one million, one hundred eighty-eight thousand, seven hundred twenty-one".