997840 has 20 divisors (see below), whose sum is σ = 2320164. Its totient is φ = 399104.

The previous prime is 997813. The next prime is 997877. The reversal of 997840 is 48799.

It is a happy number.

It can be written as a sum of positive squares in 2 ways, for example, as 529984 + 467856 = 728^2 + 684^2 .

It is a tau number, because it is divible by the number of its divisors (20).

It is an Ulam number.

It is a self number, because there is not a number n which added to its sum of digits gives 997840.

It is a congruent number.

It is an unprimeable number.

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 3 ways as a sum of consecutive naturals, for example, 6157 + ... + 6316.

2⁹⁹⁷⁸⁴⁰ is an apocalyptic number.

It is an amenable number.

997840 is an abundant number, since it is smaller than the sum of its proper divisors (1322324).

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

997840 is a wasteful number, since it uses less digits than its factorization.

997840 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 12486 (or 12480 counting only the distinct ones).

The product of its (nonzero) digits is 18144, while the sum is 37.

The square root of 997840 is about 998.9194161693. The cubic root of 997840 is about 99.9279480977.

The spelling of 997840 in words is "nine hundred ninety-seven thousand, eight hundred forty".