1721898 has 28 divisors (see below), whose sum is σ = 3875778. Its totient is φ = 573480.

The previous prime is 1721893. The next prime is 1721899. The reversal of 1721898 is 8981271.

It can be written as a sum of positive squares in only one way, i.e., 1108809 + 613089 = 1053^2 + 783^2 .

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 13 ways as a sum of consecutive naturals, for example, 868 + ... + 2048.

2^1721898 is an apocalyptic number.

1721898 is a gapful number since it is divisible by the number (18) formed by its first and last digit.

It is a practical number, because each smaller number is the sum of distinct divisors of 1721898, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1937889).

1721898 is an abundant number, since it is smaller than the sum of its proper divisors (2153880).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

1721898 is an equidigital number, since it uses as much as digits as its factorization.

1721898 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1201 (or 1186 counting only the distinct ones).

The product of its digits is 8064, while the sum is 36.

The square root of 1721898 is about 1312.2111110641. The cubic root of 1721898 is about 119.8585834100.

The spelling of 1721898 in words is "one million, seven hundred twenty-one thousand, eight hundred ninety-eight".