1399721 has 2 divisors, whose sum is σ = 1399722. Its totient is φ = 1399720.

The previous prime is 1399709. The next prime is 1399733. The reversal of 1399721 is 1279931.

It is a happy number.

It is a balanced prime because it is at equal distance from previous prime (1399709) and next prime (1399733).

It can be written as a sum of positive squares in only one way, i.e., 1297321 + 102400 = 1139^2 + 320^2 .

It is an emirp because it is prime and its reverse (1279931) is a distict prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1399721 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 (1399751) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 699860 + 699861.

It is an arithmetic number, because the mean of its divisors is an integer number (699861).

2^1399721 is an apocalyptic number.

It is an amenable number.

1399721 is a deficient number, since it is larger than the sum of its proper divisors (1).

1399721 is an equidigital number, since it uses as much as digits as its factorization.

1399721 is an evil number, because the sum of its binary digits is even.

The product of its digits is 3402, while the sum is 32.

The square root of 1399721 is about 1183.0980517269. The cubic root of 1399721 is about 111.8614624236.

The spelling of 1399721 in words is "one million, three hundred ninety-nine thousand, seven hundred twenty-one".