2164640343721 has 2 divisors, whose sum is σ = 2164640343722. Its totient is φ = 2164640343720.

The previous prime is 2164640343709. The next prime is 2164640343743. The reversal of 2164640343721 is 1273430464612.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1092576829696 + 1072063514025 = 1045264^2 + 1035405^2 .

It is a cyclic number.

It is not a de Polignac number, because 2164640343721 - 2¹⁵ = 2164640310953 is a prime.

It is not a weakly prime, because it can be changed into another prime (2164040343721) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1082320171860 + 1082320171861.

It is an arithmetic number, because the mean of its divisors is an integer number (1082320171861).

Almost surely, 2^{2164640343721} is an apocalyptic number.

It is an amenable number.

2164640343721 is a deficient number, since it is larger than the sum of its proper divisors (1).

2164640343721 is an equidigital number, since it uses as much as digits as its factorization.

2164640343721 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 580608, while the sum is 43.

The spelling of 2164640343721 in words is "two trillion, one hundred sixty-four billion, six hundred forty million, three hundred forty-three thousand, seven hundred twenty-one".