1721045 has 4 divisors (see below), whose sum is σ = 2065260. Its totient is φ = 1376832.

The previous prime is 1721023. The next prime is 1721081. The reversal of 1721045 is 5401271.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 5401271 = 157 ⋅34403.

It can be written as a sum of positive squares in 2 ways, for example, as 264196 + 1456849 = 514^2 + 1207^2 .

It is a cyclic number.

It is not a de Polignac number, because 1721045 - 2¹⁶ = 1655509 is a prime.

It is an Ulam number.

It is a Curzon number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 172100 + ... + 172109.

It is an arithmetic number, because the mean of its divisors is an integer number (516315).

2^1721045 is an apocalyptic number.

It is an amenable number.

1721045 is a deficient number, since it is larger than the sum of its proper divisors (344215).

1721045 is an equidigital number, since it uses as much as digits as its factorization.

1721045 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 344214.

The product of its (nonzero) digits is 280, while the sum is 20.

The square root of 1721045 is about 1311.8860468806. The cubic root of 1721045 is about 119.8387881494.

The spelling of 1721045 in words is "one million, seven hundred twenty-one thousand, forty-five".