1629721 has 2 divisors, whose sum is σ = 1629722. Its totient is φ = 1629720.

The previous prime is 1629689. The next prime is 1629731. The reversal of 1629721 is 1279261.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 1625625 + 4096 = 1275^2 + 64^2 .

It is a cyclic number.

It is not a de Polignac number, because 1629721 - 2⁵ = 1629689 is a prime.

It is a Chen prime.

It is a self number, because there is not a number n which added to its sum of digits gives 1629721.

It is not a weakly prime, because it can be changed into another prime (1629731) 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, 814860 + 814861.

It is an arithmetic number, because the mean of its divisors is an integer number (814861).

2^1629721 is an apocalyptic number.

It is an amenable number.

1629721 is a deficient number, since it is larger than the sum of its proper divisors (1).

1629721 is an equidigital number, since it uses as much as digits as its factorization.

1629721 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 1512, while the sum is 28.

The square root of 1629721 is about 1276.6052639716. The cubic root of 1629721 is about 117.6804771388.

The spelling of 1629721 in words is "one million, six hundred twenty-nine thousand, seven hundred twenty-one".