1257640 has 32 divisors (see below), whose sum is σ = 2954880. Its totient is φ = 480832.

The previous prime is 1257611. The next prime is 1257647. The reversal of 1257640 is 467521.

It is not an unprimeable number, because it can be changed into a prime (1257647) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 237 + ... + 1603.

It is an arithmetic number, because the mean of its divisors is an integer number (92340).

2^1257640 is an apocalyptic number.

1257640 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 1257640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1477440).

1257640 is an abundant number, since it is smaller than the sum of its proper divisors (1697240).

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

1257640 is a wasteful number, since it uses less digits than its factorization.

1257640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1401 (or 1397 counting only the distinct ones).

The product of its (nonzero) digits is 1680, while the sum is 25.

The square root of 1257640 is about 1121.4454957777. The cubic root of 1257640 is about 107.9407539706.

The spelling of 1257640 in words is "one million, two hundred fifty-seven thousand, six hundred forty".