66261933981 has 8 divisors (see below), whose sum is σ = 98165828160. Its totient is φ = 44174622636.

The previous prime is 66261933961. The next prime is 66261933989. The reversal of 66261933981 is 18933916266.

66261933981 is a `hidden beast` number, since 6 + 62 + 6 + 193 + 398 + 1 = 666.

It is not a de Polignac number, because 66261933981 - 2⁵ = 66261933949 is a prime.

It is a super-2 number, since 2×66261933981² (a number of 22 digits) contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (66261933989) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1227072825 + ... + 1227072878.

It is an arithmetic number, because the mean of its divisors is an integer number (12270728520).

Almost surely, 2^66261933981 is an apocalyptic number.

It is an amenable number.

66261933981 is a deficient number, since it is larger than the sum of its proper divisors (31903894179).

66261933981 is a wasteful number, since it uses less digits than its factorization.

66261933981 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2454145712 (or 2454145706 counting only the distinct ones).

The product of its digits is 2519424, while the sum is 54.

The spelling of 66261933981 in words is "sixty-six billion, two hundred sixty-one million, nine hundred thirty-three thousand, nine hundred eighty-one".