1820729 has 4 divisors (see below), whose sum is σ = 1832484. Its totient is φ = 1808976.

The previous prime is 1820711. The next prime is 1820737. The reversal of 1820729 is 9270281.

It is a happy number.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 1106704 + 714025 = 1052^2 + 845^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1820729 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1820759) 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 in 3 ways as a sum of consecutive naturals, for example, 5642 + ... + 5955.

It is an arithmetic number, because the mean of its divisors is an integer number (458121).

2^1820729 is an apocalyptic number.

It is an amenable number.

1820729 is a deficient number, since it is larger than the sum of its proper divisors (11755).

1820729 is a wasteful number, since it uses less digits than its factorization.

1820729 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 11754.

The product of its (nonzero) digits is 2016, while the sum is 29.

The square root of 1820729 is about 1349.3439146489. The cubic root of 1820729 is about 122.1092142153.

The spelling of 1820729 in words is "one million, eight hundred twenty thousand, seven hundred twenty-nine".