2009721 has 8 divisors (see below), whose sum is σ = 3062464. Its totient is φ = 1148400.

The previous prime is 2009719. The next prime is 2009731. The reversal of 2009721 is 1279002.

It is a happy number.

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

It is not a de Polignac number, because 2009721 - 2¹ = 2009719 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (21), and also a Moran number because the ratio is a prime number: 95701 = 2009721 / (2 + 0 + 0 + 9 + 7 + 2 + 1).

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (2009731) 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 in 7 ways as a sum of consecutive naturals, for example, 47830 + ... + 47871.

It is an arithmetic number, because the mean of its divisors is an integer number (382808).

2^2009721 is an apocalyptic number.

2009721 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

It is an amenable number.

2009721 is a deficient number, since it is larger than the sum of its proper divisors (1052743).

2009721 is an equidigital number, since it uses as much as digits as its factorization.

2009721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 95711.

The product of its (nonzero) digits is 252, while the sum is 21.

The square root of 2009721 is about 1417.6462887477. The cubic root of 2009721 is about 126.1959033667.

The spelling of 2009721 in words is "two million, nine thousand, seven hundred twenty-one".