66133781 has 6 divisors (see below), whose sum is σ = 76931190. Its totient is φ = 56686056.

The previous prime is 66133751. The next prime is 66133783. The reversal of 66133781 is 18733166.

It can be written as a sum of positive squares in only one way, i.e., 57896881 + 8236900 = 7609^2 + 2870^2 .

It is a de Polignac number, because none of the positive numbers 2^k-66133781 is a prime.

It is a super-2 number, since 2×66133781² = 8747353978711922, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (66133783) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 674786 + ... + 674883.

It is an arithmetic number, because the mean of its divisors is an integer number (12821865).

Almost surely, 2^66133781 is an apocalyptic number.

It is an amenable number.

66133781 is a deficient number, since it is larger than the sum of its proper divisors (10797409).

66133781 is a wasteful number, since it uses less digits than its factorization.

66133781 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1349683 (or 1349676 counting only the distinct ones).

The product of its digits is 18144, while the sum is 35.

The square root of 66133781 is about 8132.2678878650. The cubic root of 66133781 is about 404.3968688559.

The spelling of 66133781 in words is "sixty-six million, one hundred thirty-three thousand, seven hundred eighty-one".