66021601 has 2 divisors, whose sum is σ = 66021602. Its totient is φ = 66021600.

The previous prime is 66021589. The next prime is 66021611. The reversal of 66021601 is 10612066.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 33074001 + 32947600 = 5751^2 + 5740^2 .

It is a cyclic number.

It is not a de Polignac number, because 66021601 - 2¹⁷ = 65890529 is a prime.

It is a super-3 number, since 3×66021601³ (a number of 24 digits) contains 333 as substring.

It is not a weakly prime, because it can be changed into another prime (66021611) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 33010800 + 33010801.

It is an arithmetic number, because the mean of its divisors is an integer number (33010801).

Almost surely, 2^66021601 is an apocalyptic number.

It is an amenable number.

66021601 is a deficient number, since it is larger than the sum of its proper divisors (1).

66021601 is an equidigital number, since it uses as much as digits as its factorization.

66021601 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 432, while the sum is 22.

The square root of 66021601 is about 8125.3677455239. The cubic root of 66021601 is about 404.1680855490.

Adding to 66021601 its reverse (10612066), we get a palindrome (76633667).

The spelling of 66021601 in words is "sixty-six million, twenty-one thousand, six hundred one".