1990721 has 8 divisors (see below), whose sum is σ = 2042880. Its totient is φ = 1939392.

The previous prime is 1990693. The next prime is 1990753. The reversal of 1990721 is 1270991.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 1990721 - 2⁶ = 1990657 is a prime.

It is an Ulam number.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1990321) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 8816 + ... + 9038.

It is an arithmetic number, because the mean of its divisors is an integer number (255360).

2^1990721 is an apocalyptic number.

It is an amenable number.

1990721 is a deficient number, since it is larger than the sum of its proper divisors (52159).

1990721 is a wasteful number, since it uses less digits than its factorization.

1990721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 415.

The product of its (nonzero) digits is 1134, while the sum is 29.

The square root of 1990721 is about 1410.9291264979. The cubic root of 1990721 is about 125.7969560895.

The spelling of 1990721 in words is "one million, nine hundred ninety thousand, seven hundred twenty-one".