2491656840 has 144 divisors (see below), whose sum is σ = 8209082700. Its totient is φ = 655439616.

The previous prime is 2491656823. The next prime is 2491656841. The reversal of 2491656840 is 486561942.

2491656840 is a `hidden beast` number, since 2 + 49 + 1 + 6 + 568 + 40 = 666.

It can be written as a sum of positive squares in 2 ways, for example, as 2113976484 + 377680356 = 45978^2 + 19434^2 .

It is a Harshad number since it is a multiple of its sum of digits (45).

It is not an unprimeable number, because it can be changed into a prime (2491656841) by changing a digit.

It is a polite number, since it can be written in 35 ways as a sum of consecutive naturals, for example, 2246206 + ... + 2247314.

Almost surely, 2^2491656840 is an apocalyptic number.

2491656840 is a gapful number since it is divisible by the number (20) 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 2491656840, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (4104541350).

2491656840 is an abundant number, since it is smaller than the sum of its proper divisors (5717425860).

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

2491656840 is a wasteful number, since it uses less digits than its factorization.

2491656840 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1284 (or 1198 counting only the distinct ones).

The product of its (nonzero) digits is 414720, while the sum is 45.

The square root of 2491656840 is about 49916.4986752877. The cubic root of 2491656840 is about 1355.6973376241.

The spelling of 2491656840 in words is "two billion, four hundred ninety-one million, six hundred fifty-six thousand, eight hundred forty".