1721731 has 4 divisors (see below), whose sum is σ = 1878264. Its totient is φ = 1565200.

The previous prime is 1721729. The next prime is 1721749. The reversal of 1721731 is 1371271.

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

It is a cyclic number.

It is not a de Polignac number, because 1721731 - 2¹ = 1721729 is a prime.

It is a super-2 number, since 2×1721731² = 5928715272722, which contains 22 as substring.

It is a Smith number, since the sum of its digits (22) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

1721731 is a lucky number.

It is a nialpdrome in base 11.

It is not an unprimeable number, because it can be changed into a prime (1721831) 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, 78250 + ... + 78271.

It is an arithmetic number, because the mean of its divisors is an integer number (469566).

2^1721731 is an apocalyptic number.

1721731 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

1721731 is a deficient number, since it is larger than the sum of its proper divisors (156533).

1721731 is a wasteful number, since it uses less digits than its factorization.

1721731 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 156532.

The product of its digits is 294, while the sum is 22.

The square root of 1721731 is about 1312.1474764675. The cubic root of 1721731 is about 119.8547084166.

The spelling of 1721731 in words is "one million, seven hundred twenty-one thousand, seven hundred thirty-one".