2105664515661 has 32 divisors (see below), whose sum is σ = 3293510906880. Its totient is φ = 1171788339456.

The previous prime is 2105664515657. The next prime is 2105664515677. The reversal of 2105664515661 is 1665154665012.

It is not a de Polignac number, because 2105664515661 - 2² = 2105664515657 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 2105664515661.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (2105664515651) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 7808956 + ... + 8074101.

It is an arithmetic number, because the mean of its divisors is an integer number (102922215840).

Almost surely, 2^{2105664515661} is an apocalyptic number.

2105664515661 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

It is an amenable number.

2105664515661 is a deficient number, since it is larger than the sum of its proper divisors (1187846391219).

2105664515661 is a wasteful number, since it uses less digits than its factorization.

2105664515661 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 15883233.

The product of its (nonzero) digits is 1296000, while the sum is 48.

The spelling of 2105664515661 in words is "two trillion, one hundred five billion, six hundred sixty-four million, five hundred fifteen thousand, six hundred sixty-one".