66443621401 has 2 divisors, whose sum is σ = 66443621402. Its totient is φ = 66443621400.

The previous prime is 66443621399. The next prime is 66443621407. The reversal of 66443621401 is 10412634466.

66443621401 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 59846283225 + 6597338176 = 244635^2 + 81224^2 .

It is a cyclic number.

It is not a de Polignac number, because 66443621401 - 2¹ = 66443621399 is a prime.

Together with 66443621399, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (66443621407) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 33221810700 + 33221810701.

It is an arithmetic number, because the mean of its divisors is an integer number (33221810701).

Almost surely, 2^66443621401 is an apocalyptic number.

It is an amenable number.

66443621401 is a deficient number, since it is larger than the sum of its proper divisors (1).

66443621401 is an equidigital number, since it uses as much as digits as its factorization.

66443621401 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 82944, while the sum is 37.

The spelling of 66443621401 in words is "sixty-six billion, four hundred forty-three million, six hundred twenty-one thousand, four hundred one".