2781640 has 32 divisors (see below), whose sum is σ = 6308280. Its totient is φ = 1103872.

The previous prime is 2781637. The next prime is 2781677. The reversal of 2781640 is 461872.

It can be written as a sum of positive squares in 4 ways, for example, as 2683044 + 98596 = 1638^2 + 314^2 .

It is a junction number, because it is equal to n+sod(n) for n = 2781599 and 2781608.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 7704 + ... + 8056.

2^2781640 is an apocalyptic number.

2781640 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

2781640 is an abundant number, since it is smaller than the sum of its proper divisors (3526640).

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

2781640 is a wasteful number, since it uses less digits than its factorization.

2781640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 561 (or 557 counting only the distinct ones).

The product of its (nonzero) digits is 2688, while the sum is 28.

The square root of 2781640 is about 1667.8249308606. The cubic root of 2781640 is about 140.6372311995.

The spelling of 2781640 in words is "two million, seven hundred eighty-one thousand, six hundred forty".