2168357661 has 8 divisors (see below), whose sum is σ = 3212381760. Its totient is φ = 1445571756.

The previous prime is 2168357647. The next prime is 2168357687. The reversal of 2168357661 is 1667538612.

2168357661 is a `hidden beast` number, since 2 + 16 + 8 + 3 + 576 + 61 = 666.

It is not a de Polignac number, because 2168357661 - 2⁵ = 2168357629 is a prime.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (2168357761) 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, 40154745 + ... + 40154798.

It is an arithmetic number, because the mean of its divisors is an integer number (401547720).

Almost surely, 2^2168357661 is an apocalyptic number.

It is an amenable number.

2168357661 is a deficient number, since it is larger than the sum of its proper divisors (1044024099).

2168357661 is an equidigital number, since it uses as much as digits as its factorization.

2168357661 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 80309552 (or 80309546 counting only the distinct ones).

The product of its digits is 362880, while the sum is 45.

The square root of 2168357661 is about 46565.6274627541. The cubic root of 2168357661 is about 1294.3258937479.

The spelling of 2168357661 in words is "two billion, one hundred sixty-eight million, three hundred fifty-seven thousand, six hundred sixty-one".