1980721 has 16 divisors (see below), whose sum is σ = 2232576. Its totient is φ = 1748736.

The previous prime is 1980707. The next prime is 1980743. The reversal of 1980721 is 1270891.

It is a cyclic number.

It is not a de Polignac number, because 1980721 - 2¹¹ = 1978673 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 1980721.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1980701) 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 15 ways as a sum of consecutive naturals, for example, 29530 + ... + 29596.

It is an arithmetic number, because the mean of its divisors is an integer number (139536).

2^1980721 is an apocalyptic number.

It is an amenable number.

1980721 is a deficient number, since it is larger than the sum of its proper divisors (251855).

1980721 is a wasteful number, since it uses less digits than its factorization.

1980721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 168.

The product of its (nonzero) digits is 1008, while the sum is 28.

The square root of 1980721 is about 1407.3809008225. The cubic root of 1980721 is about 125.5859635483.

It can be divided in two parts, 1980 and 721, that added together give a triangular number (2701 = T₇₃).

The spelling of 1980721 in words is "one million, nine hundred eighty thousand, seven hundred twenty-one".