1721897 has 4 divisors (see below), whose sum is σ = 1726080. Its totient is φ = 1717716.

The previous prime is 1721893. The next prime is 1721899. The reversal of 1721897 is 7981271.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 7981271 = 911 ⋅8761.

It is a cyclic number.

It is not a de Polignac number, because 1721897 - 2² = 1721893 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1721891) 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, 1397 + ... + 2322.

It is an arithmetic number, because the mean of its divisors is an integer number (431520).

2^1721897 is an apocalyptic number.

It is an amenable number.

1721897 is a deficient number, since it is larger than the sum of its proper divisors (4183).

1721897 is an equidigital number, since it uses as much as digits as its factorization.

1721897 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4182.

The product of its digits is 7056, while the sum is 35.

The square root of 1721897 is about 1312.2107300278. The cubic root of 1721897 is about 119.8585602072.

The spelling of 1721897 in words is "one million, seven hundred twenty-one thousand, eight hundred ninety-seven".