66581801 has 16 divisors (see below), whose sum is σ = 78503040. Its totient is φ = 55672320.

The previous prime is 66581791. The next prime is 66581807. The reversal of 66581801 is 10818566.

It is not a de Polignac number, because 66581801 - 2⁶ = 66581737 is a prime.

It is not an unprimeable number, because it can be changed into a prime (66581807) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 49820 + ... + 51138.

It is an arithmetic number, because the mean of its divisors is an integer number (4906440).

Almost surely, 2^66581801 is an apocalyptic number.

It is an amenable number.

66581801 is a deficient number, since it is larger than the sum of its proper divisors (11921239).

66581801 is a wasteful number, since it uses less digits than its factorization.

66581801 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1696.

The product of its (nonzero) digits is 11520, while the sum is 35.

The square root of 66581801 is about 8159.7672148169. The cubic root of 66581801 is about 405.3080032690.

It can be divided in two parts, 665 and 81801, that multiplied together give a triangular number (54397665 = T₁₀₄₃₀).

The spelling of 66581801 in words is "sixty-six million, five hundred eighty-one thousand, eight hundred one".