2168657521 has 2 divisors, whose sum is σ = 2168657522. Its totient is φ = 2168657520.

The previous prime is 2168657507. The next prime is 2168657527. The reversal of 2168657521 is 1257568612.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 1947986496 + 220671025 = 44136^2 + 14855^2 .

It is a cyclic number.

It is not a de Polignac number, because 2168657521 - 2¹⁵ = 2168624753 is a prime.

It is not a weakly prime, because it can be changed into another prime (2168657527) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1084328760 + 1084328761.

It is an arithmetic number, because the mean of its divisors is an integer number (1084328761).

Almost surely, 2^2168657521 is an apocalyptic number.

It is an amenable number.

2168657521 is a deficient number, since it is larger than the sum of its proper divisors (1).

2168657521 is an equidigital number, since it uses as much as digits as its factorization.

2168657521 is an evil number, because the sum of its binary digits is even.

The product of its digits is 201600, while the sum is 43.

The square root of 2168657521 is about 46568.8471083406. The cubic root of 2168657521 is about 1294.3855546731.

The spelling of 2168657521 in words is "two billion, one hundred sixty-eight million, six hundred fifty-seven thousand, five hundred twenty-one".