2640667681 has 8 divisors (see below), whose sum is σ = 2821654440. Its totient is φ = 2462531328.

The previous prime is 2640667669. The next prime is 2640667691. The reversal of 2640667681 is 1867660462.

It can be written as a sum of positive squares in 4 ways, for example, as 1338901281 + 1301766400 = 36591^2 + 36080^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a de Polignac number, because none of the positive numbers 2^k-2640667681 is a prime.

It is a super-2 number, since 2×2640667681² = 13946251602955835522, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (2640667691) 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, 710686 + ... + 714391.

It is an arithmetic number, because the mean of its divisors is an integer number (352706805).

Almost surely, 2^2640667681 is an apocalyptic number.

It is an amenable number.

2640667681 is a deficient number, since it is larger than the sum of its proper divisors (180986759).

2640667681 is a wasteful number, since it uses less digits than its factorization.

2640667681 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1425203.

The product of its (nonzero) digits is 580608, while the sum is 46.

The square root of 2640667681 is about 51387.4272658206. The cubic root of 2640667681 is about 1382.2011502794.

The spelling of 2640667681 in words is "two billion, six hundred forty million, six hundred sixty-seven thousand, six hundred eighty-one".