1721668 has 24 divisors (see below), whose sum is σ = 3284568. Its totient is φ = 784896.

The previous prime is 1721659. The next prime is 1721683. The reversal of 1721668 is 8661271.

It can be written as a sum of positive squares in 4 ways, for example, as 36864 + 1684804 = 192^2 + 1298^2 .

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 5730 + ... + 6022.

It is an arithmetic number, because the mean of its divisors is an integer number (136857).

2^1721668 is an apocalyptic number.

It is an amenable number.

1721668 is a deficient number, since it is larger than the sum of its proper divisors (1562900).

1721668 is a wasteful number, since it uses less digits than its factorization.

1721668 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 423 (or 421 counting only the distinct ones).

The product of its digits is 4032, while the sum is 31.

The square root of 1721668 is about 1312.1234698000. The cubic root of 1721668 is about 119.8532465276.

The spelling of 1721668 in words is "one million, seven hundred twenty-one thousand, six hundred sixty-eight".