1721919 has 4 divisors (see below), whose sum is σ = 2295896. Its totient is φ = 1147944.

The previous prime is 1721911. The next prime is 1721921. The reversal of 1721919 is 9191271.

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

It is not a de Polignac number, because 1721919 - 2³ = 1721911 is a prime.

It is a super-2 number, since 2×1721919² = 5930010085122, which contains 22 as substring.

It is a D-number.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1721911) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 286984 + ... + 286989.

It is an arithmetic number, because the mean of its divisors is an integer number (573974).

2^1721919 is an apocalyptic number.

1721919 is a deficient number, since it is larger than the sum of its proper divisors (573977).

1721919 is an equidigital number, since it uses as much as digits as its factorization.

1721919 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 573976.

The product of its digits is 1134, while the sum is 30.

The square root of 1721919 is about 1312.2191128009. The cubic root of 1721919 is about 119.8590706669.

The spelling of 1721919 in words is "one million, seven hundred twenty-one thousand, nine hundred nineteen".