1243640 has 16 divisors (see below), whose sum is σ = 2798280. Its totient is φ = 497440.

The previous prime is 1243639. The next prime is 1243643. The reversal of 1243640 is 463421.

It is a happy number.

It is a Harshad number since it is a multiple of its sum of digits (20).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1243643) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 15506 + ... + 15585.

2^1243640 is an apocalyptic number.

1243640 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

1243640 is an abundant number, since it is smaller than the sum of its proper divisors (1554640).

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

1243640 is a wasteful number, since it uses less digits than its factorization.

1243640 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 31102 (or 31098 counting only the distinct ones).

The product of its (nonzero) digits is 576, while the sum is 20.

The square root of 1243640 is about 1115.1860831269. The cubic root of 1243640 is about 107.5387277085.

The spelling of 1243640 in words is "one million, two hundred forty-three thousand, six hundred forty".