66402561 has 16 divisors (see below), whose sum is σ = 95148864. Its totient is φ = 41040384.

The previous prime is 66402559. The next prime is 66402563. The reversal of 66402561 is 16520466.

66402561 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is an interprime number because it is at equal distance from previous prime (66402559) and next prime (66402563).

It is not a de Polignac number, because 66402561 - 2¹ = 66402559 is a prime.

It is not an unprimeable number, because it can be changed into a prime (66402563) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 6300 + ... + 13133.

It is an arithmetic number, because the mean of its divisors is an integer number (5946804).

Almost surely, 2^66402561 is an apocalyptic number.

It is an amenable number.

66402561 is a deficient number, since it is larger than the sum of its proper divisors (28746303).

66402561 is a wasteful number, since it uses less digits than its factorization.

66402561 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 19520.

The product of its (nonzero) digits is 8640, while the sum is 30.

The square root of 66402561 is about 8148.7766566522. The cubic root of 66402561 is about 404.9439763994.

The spelling of 66402561 in words is "sixty-six million, four hundred two thousand, five hundred sixty-one".