2661345651999 has 4 divisors (see below), whose sum is σ = 3548460869336. Its totient is φ = 1774230434664.

The previous prime is 2661345651917. The next prime is 2661345652061. The reversal of 2661345651999 is 9991565431662.

It is a semiprime because it is the product of two primes.

It is not a de Polignac number, because 2661345651999 - 2⁷ = 2661345651871 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (2661345651299) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 443557608664 + ... + 443557608669.

It is an arithmetic number, because the mean of its divisors is an integer number (887115217334).

Almost surely, 2^{2661345651999} is an apocalyptic number.

2661345651999 is a deficient number, since it is larger than the sum of its proper divisors (887115217337).

2661345651999 is an equidigital number, since it uses as much as digits as its factorization.

2661345651999 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 887115217336.

The product of its digits is 94478400, while the sum is 66.

The spelling of 2661345651999 in words is "two trillion, six hundred sixty-one billion, three hundred forty-five million, six hundred fifty-one thousand, nine hundred ninety-nine".