1539721 has 2 divisors, whose sum is σ = 1539722. Its totient is φ = 1539720.

The previous prime is 1539719. The next prime is 1539731. The reversal of 1539721 is 1279351.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1166400 + 373321 = 1080^2 + 611^2 .

It is a cyclic number.

It is not a de Polignac number, because 1539721 - 2¹ = 1539719 is a prime.

Together with 1539719, it forms a pair of twin primes.

1539721 is a lucky number.

It is a self number, because there is not a number n which added to its sum of digits gives 1539721.

It is not a weakly prime, because it can be changed into another prime (1539731) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 769860 + 769861.

It is an arithmetic number, because the mean of its divisors is an integer number (769861).

2^1539721 is an apocalyptic number.

It is an amenable number.

1539721 is a deficient number, since it is larger than the sum of its proper divisors (1).

1539721 is an equidigital number, since it uses as much as digits as its factorization.

1539721 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 1890, while the sum is 28.

The square root of 1539721 is about 1240.8549472037. The cubic root of 1539721 is about 115.4730608136.

The spelling of 1539721 in words is "one million, five hundred thirty-nine thousand, seven hundred twenty-one".