66217697281 has 16 divisors (see below), whose sum is σ = 70190729728. Its totient is φ = 62381145600.

The previous prime is 66217697269. The next prime is 66217697303. The reversal of 66217697281 is 18279671266.

It is a cyclic number.

It is not a de Polignac number, because 66217697281 - 2¹⁷ = 66217566209 is a prime.

It is a super-2 number, since 2×66217697281² (a number of 22 digits) contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (66217697251) 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, 2926 + ... + 363928.

It is an arithmetic number, because the mean of its divisors is an integer number (4386920608).

Almost surely, 2^66217697281 is an apocalyptic number.

66217697281 is a gapful number since it is divisible by the number (61) formed by its first and last digit.

It is an amenable number.

66217697281 is a deficient number, since it is larger than the sum of its proper divisors (3973032447).

66217697281 is a wasteful number, since it uses less digits than its factorization.

66217697281 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 361192.

The product of its digits is 3048192, while the sum is 55.

The spelling of 66217697281 in words is "sixty-six billion, two hundred seventeen million, six hundred ninety-seven thousand, two hundred eighty-one".