2640905691 has 8 divisors (see below), whose sum is σ = 3548934144. Its totient is φ = 1746740520.

The previous prime is 2640905671. The next prime is 2640905713. The reversal of 2640905691 is 1965090462.

It is a happy number.

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

It is not a de Polignac number, because 2640905691 - 2²² = 2636711387 is a prime.

It is a super-3 number, since 3×2640905691³ (a number of 29 digits) contains 333 as substring.

It is not an unprimeable number, because it can be changed into a prime (2640905671) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 3465375 + ... + 3466136.

It is an arithmetic number, because the mean of its divisors is an integer number (443616768).

Almost surely, 2^2640905691 is an apocalyptic number.

2640905691 is a deficient number, since it is larger than the sum of its proper divisors (908028453).

2640905691 is a wasteful number, since it uses less digits than its factorization.

2640905691 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6931641.

The product of its (nonzero) digits is 116640, while the sum is 42.

The square root of 2640905691 is about 51389.7430524808. The cubic root of 2640905691 is about 1382.2426761171.

The spelling of 2640905691 in words is "two billion, six hundred forty million, nine hundred five thousand, six hundred ninety-one".