1996721 has 2 divisors, whose sum is σ = 1996722. Its totient is φ = 1996720.

The previous prime is 1996717. The next prime is 1996723. The reversal of 1996721 is 1276991.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 1852321 + 144400 = 1361^2 + 380^2 .

It is a cyclic number.

It is not a de Polignac number, because 1996721 - 2² = 1996717 is a prime.

It is a Sophie Germain prime.

Together with 1996723, it forms a pair of twin primes.

It is a Chen prime.

It is a Curzon number.

It is not a weakly prime, because it can be changed into another prime (1996723) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 998360 + 998361.

It is an arithmetic number, because the mean of its divisors is an integer number (998361).

2^1996721 is an apocalyptic number.

It is an amenable number.

1996721 is a deficient number, since it is larger than the sum of its proper divisors (1).

1996721 is an equidigital number, since it uses as much as digits as its factorization.

1996721 is an evil number, because the sum of its binary digits is even.

The product of its digits is 6804, while the sum is 35.

The square root of 1996721 is about 1413.0537852467. The cubic root of 1996721 is about 125.9232126407.

The spelling of 1996721 in words is "one million, nine hundred ninety-six thousand, seven hundred twenty-one".