1213840 has 20 divisors (see below), whose sum is σ = 2822364. Its totient is φ = 485504.

The previous prime is 1213837. The next prime is 1213841. The reversal of 1213840 is 483121.

It can be written as a sum of positive squares in 2 ways, for example, as 824464 + 389376 = 908^2 + 624^2 .

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

It is not an unprimeable number, because it can be changed into a prime (1213841) 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 3 ways as a sum of consecutive naturals, for example, 7507 + ... + 7666.

2^1213840 is an apocalyptic number.

1213840 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

1213840 is an abundant number, since it is smaller than the sum of its proper divisors (1608524).

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

1213840 is a wasteful number, since it uses less digits than its factorization.

1213840 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 15186 (or 15180 counting only the distinct ones).

The product of its (nonzero) digits is 192, while the sum is 19.

The square root of 1213840 is about 1101.7440719151. The cubic root of 1213840 is about 106.6728295050.

Adding to 1213840 its reverse (483121), we get a palindrome (1696961).

The spelling of 1213840 in words is "one million, two hundred thirteen thousand, eight hundred forty".