1165721 has 2 divisors, whose sum is σ = 1165722. Its totient is φ = 1165720.

The previous prime is 1165711. The next prime is 1165727. The reversal of 1165721 is 1275611.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 1125721 + 40000 = 1061^2 + 200^2 .

It is an emirp because it is prime and its reverse (1275611) is a distict prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1165721 is a prime.

It is a Sophie Germain prime.

It is a Chen prime.

It is a Curzon number.

It is not a weakly prime, because it can be changed into another prime (1165727) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 582860 + 582861.

It is an arithmetic number, because the mean of its divisors is an integer number (582861).

2^1165721 is an apocalyptic number.

It is an amenable number.

1165721 is a deficient number, since it is larger than the sum of its proper divisors (1).

1165721 is an equidigital number, since it uses as much as digits as its factorization.

1165721 is an evil number, because the sum of its binary digits is even.

The product of its digits is 420, while the sum is 23.

The square root of 1165721 is about 1079.6856023862. The cubic root of 1165721 is about 105.2442086021.

The spelling of 1165721 in words is "one million, one hundred sixty-five thousand, seven hundred twenty-one".