1997440 has 32 divisors (see below), whose sum is σ = 4776660. Its totient is φ = 798720.

The previous prime is 1997431. The next prime is 1997441. The reversal of 1997440 is 447991.

It can be written as a sum of positive squares in 2 ways, for example, as 1617984 + 379456 = 1272^2 + 616^2 .

It is a tau number, because it is divible by the number of its divisors (32).

It is an Ulam number.

It is a junction number, because it is equal to n+sod(n) for n = 1997396 and 1997405.

It is not an unprimeable number, because it can be changed into a prime (1997441) 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, 921 + ... + 2200.

2^1997440 is an apocalyptic number.

1997440 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

1997440 is an abundant number, since it is smaller than the sum of its proper divisors (2779220).

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

1997440 is an equidigital number, since it uses as much as digits as its factorization.

1997440 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3140 (or 3128 counting only the distinct ones).

The product of its (nonzero) digits is 9072, while the sum is 34.

The square root of 1997440 is about 1413.3081758767. The cubic root of 1997440 is about 125.9383254055.

The spelling of 1997440 in words is "one million, nine hundred ninety-seven thousand, four hundred forty".