21416664461 has 2 divisors, whose sum is σ = 21416664462. Its totient is φ = 21416664460.

The previous prime is 21416664391. The next prime is 21416664469. The reversal of 21416664461 is 16446661412.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 21377364100 + 39300361 = 146210^2 + 6269^2 .

It is a cyclic number.

It is not a de Polignac number, because 21416664461 - 2¹⁸ = 21416402317 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21416664469) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10708332230 + 10708332231.

It is an arithmetic number, because the mean of its divisors is an integer number (10708332231).

Almost surely, 2^21416664461 is an apocalyptic number.

It is an amenable number.

21416664461 is a deficient number, since it is larger than the sum of its proper divisors (1).

21416664461 is an equidigital number, since it uses as much as digits as its factorization.

21416664461 is an evil number, because the sum of its binary digits is even.

The product of its digits is 165888, while the sum is 41.

The spelling of 21416664461 in words is "twenty-one billion, four hundred sixteen million, six hundred sixty-four thousand, four hundred sixty-one".