1722640 has 40 divisors (see below), whose sum is σ = 4082328. Its totient is φ = 675840.

The previous prime is 1722619. The next prime is 1722647. The reversal of 1722640 is 462271.

It can be written as a sum of positive squares in 4 ways, for example, as 1296 + 1721344 = 36^2 + 1312^2 .

It is a tau number, because it is divible by the number of its divisors (40).

It is a nialpdrome in base 8.

It is not an unprimeable number, because it can be changed into a prime (1722647) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 4704 + ... + 5056.

2^1722640 is an apocalyptic number.

1722640 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 1722640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (2041164).

1722640 is an abundant number, since it is smaller than the sum of its proper divisors (2359688).

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

1722640 is a wasteful number, since it uses less digits than its factorization.

1722640 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 427 (or 421 counting only the distinct ones).

The product of its (nonzero) digits is 672, while the sum is 22.

The square root of 1722640 is about 1312.4938095092. The cubic root of 1722640 is about 119.8757974179.

The spelling of 1722640 in words is "one million, seven hundred twenty-two thousand, six hundred forty".