1901721 has 8 divisors (see below), whose sum is σ = 2551840. Its totient is φ = 1259712.

The previous prime is 1901719. The next prime is 1901749. The reversal of 1901721 is 1271091.

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

It is not a de Polignac number, because 1901721 - 2¹ = 1901719 is a prime.

It is a Duffinian number.

1901721 is a lucky number.

It is not an unprimeable number, because it can be changed into a prime (1901771) 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, 1456 + ... + 2433.

It is an arithmetic number, because the mean of its divisors is an integer number (318980).

2^1901721 is an apocalyptic number.

It is an amenable number.

1901721 is a deficient number, since it is larger than the sum of its proper divisors (650119).

1901721 is a wasteful number, since it uses less digits than its factorization.

1901721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4055.

The product of its (nonzero) digits is 126, while the sum is 21.

The square root of 1901721 is about 1379.0290062214. The cubic root of 1901721 is about 123.8936175685.

The spelling of 1901721 in words is "one million, nine hundred one thousand, seven hundred twenty-one".