1256640 has 224 divisors, whose sum is σ = 5266944. Its totient is φ = 245760.

The previous prime is 1256621. The next prime is 1256659. The reversal of 1256640 is 466521.

It is a Cunningham number, because it is equal to 1121²-1.

It is an interprime number because it is at equal distance from previous prime (1256621) and next prime (1256659).

It is a tau number, because it is divible by the number of its divisors (224).

It is a Harshad number since it is a multiple of its sum of digits (24).

It is a self number, because there is not a number n which added to its sum of digits gives 1256640.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 73912 + ... + 73928.

2^1256640 is an apocalyptic number.

1256640 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 1256640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (2633472).

1256640 is an abundant number, since it is smaller than the sum of its proper divisors (4010304).

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

1256640 is a wasteful number, since it uses less digits than its factorization.

1256640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 55 (or 45 counting only the distinct ones).

The product of its (nonzero) digits is 1440, while the sum is 24.

The square root of 1256640 is about 1120.9995539696. Note that the first 3 decimals coincide. The cubic root of 1256640 is about 107.9121370436.

The spelling of 1256640 in words is "one million, two hundred fifty-six thousand, six hundred forty".