1721531 has 8 divisors (see below), whose sum is σ = 1976064. Its totient is φ = 1469160.

The previous prime is 1721521. The next prime is 1721543. The reversal of 1721531 is 1351271.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a de Polignac number, because none of the positive numbers 2^k-1721531 is a prime.

It is a super-2 number, since 2×1721531² = 5927337967922, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1721501) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1946 + ... + 2688.

It is an arithmetic number, because the mean of its divisors is an integer number (247008).

2^1721531 is an apocalyptic number.

1721531 is a deficient number, since it is larger than the sum of its proper divisors (254533).

1721531 is an equidigital number, since it uses as much as digits as its factorization.

1721531 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1081.

The product of its digits is 210, while the sum is 20.

The square root of 1721531 is about 1312.0712633085. The cubic root of 1721531 is about 119.8500673761.

The spelling of 1721531 in words is "one million, seven hundred twenty-one thousand, five hundred thirty-one".