1290640 has 80 divisors (see below), whose sum is σ = 3468528. Its totient is φ = 442368.

The previous prime is 1290637. The next prime is 1290643. The reversal of 1290640 is 460921.

It is an interprime number because it is at equal distance from previous prime (1290637) and next prime (1290643).

It can be written as a sum of positive squares in 8 ways, for example, as 9216 + 1281424 = 96^2 + 1132^2 .

It is a tau number, because it is divible by the number of its divisors (80).

It is not an unprimeable number, because it can be changed into a prime (1290643) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 17644 + ... + 17716.

2^1290640 is an apocalyptic number.

1290640 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 1290640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1734264).

1290640 is an abundant number, since it is smaller than the sum of its proper divisors (2177888).

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

1290640 is a wasteful number, since it uses less digits than its factorization.

1290640 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 116 (or 110 counting only the distinct ones).

The product of its (nonzero) digits is 432, while the sum is 22.

The square root of 1290640 is about 1136.0633785137. The cubic root of 1290640 is about 108.8767228452.

The spelling of 1290640 in words is "one million, two hundred ninety thousand, six hundred forty".