2581640 has 32 divisors (see below), whose sum is σ = 5854680. Its totient is φ = 1024512.

The previous prime is 2581639. The next prime is 2581643. The reversal of 2581640 is 461852.

2581640 = 208² + 209² + ... + 255².

It can be written as a sum of positive squares in 4 ways, for example, as 1249924 + 1331716 = 1118^2 + 1154^2 .

It is not an unprimeable number, because it can be changed into a prime (2581643) 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, 9182 + ... + 9458.

2^2581640 is an apocalyptic number.

2581640 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

2581640 is an abundant number, since it is smaller than the sum of its proper divisors (3273040).

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

2581640 is a wasteful number, since it uses less digits than its factorization.

2581640 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 521 (or 517 counting only the distinct ones).

The product of its (nonzero) digits is 1920, while the sum is 26.

The square root of 2581640 is about 1606.7482690204. The cubic root of 2581640 is about 137.1824517785.

The spelling of 2581640 in words is "two million, five hundred eighty-one thousand, six hundred forty".