2187566640521 has 2 divisors, whose sum is σ = 2187566640522. Its totient is φ = 2187566640520.

The previous prime is 2187566640509. The next prime is 2187566640583. The reversal of 2187566640521 is 1250466657812.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 2135280787600 + 52285852921 = 1461260^2 + 228661^2 .

It is a cyclic number.

It is not a de Polignac number, because 2187566640521 - 2¹⁴ = 2187566624137 is a prime.

It is not a weakly prime, because it can be changed into another prime (2187566640221) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1093783320260 + 1093783320261.

It is an arithmetic number, because the mean of its divisors is an integer number (1093783320261).

Almost surely, 2^{2187566640521} is an apocalyptic number.

It is an amenable number.

2187566640521 is a deficient number, since it is larger than the sum of its proper divisors (1).

2187566640521 is an equidigital number, since it uses as much as digits as its factorization.

2187566640521 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 4838400, while the sum is 53.

The spelling of 2187566640521 in words is "two trillion, one hundred eighty-seven billion, five hundred sixty-six million, six hundred forty thousand, five hundred twenty-one".