1720845 has 40 divisors (see below), whose sum is σ = 3531264. Its totient is φ = 785376.

The previous prime is 1720843. The next prime is 1720847. The reversal of 1720845 is 5480271.

It is an interprime number because it is at equal distance from previous prime (1720843) and next prime (1720847).

It is not a de Polignac number, because 1720845 - 2¹ = 1720843 is a prime.

It is a super-2 number, since 2×1720845² = 5922615028050, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is an Ulam number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1720843) by changing a digit.

It is a polite number, since it can be written in 39 ways as a sum of consecutive naturals, for example, 2532 + ... + 3138.

2^1720845 is an apocalyptic number.

1720845 is a gapful number since it is divisible by the number (15) formed by its first and last digit.

It is an amenable number.

1720845 is an abundant number, since it is smaller than the sum of its proper divisors (1810419).

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

1720845 is an equidigital number, since it uses as much as digits as its factorization.

1720845 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 631 (or 622 counting only the distinct ones).

The product of its (nonzero) digits is 2240, while the sum is 27.

The square root of 1720845 is about 1311.8098185332. The cubic root of 1720845 is about 119.8341458757.

The spelling of 1720845 in words is "one million, seven hundred twenty thousand, eight hundred forty-five".