66136785491 has 32 divisors (see below), whose sum is σ = 77213859840. Its totient is φ = 55480269600.

The previous prime is 66136785479. The next prime is 66136785511. The reversal of 66136785491 is 19458763166.

66136785491 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is not a de Polignac number, because 66136785491 - 2³⁰ = 65063043667 is a prime.

It is a super-2 number, since 2×66136785491² (a number of 22 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (66136785191) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 63653750 + ... + 63654788.

It is an arithmetic number, because the mean of its divisors is an integer number (2412933120).

Almost surely, 2^66136785491 is an apocalyptic number.

66136785491 is a deficient number, since it is larger than the sum of its proper divisors (11077074349).

66136785491 is a wasteful number, since it uses less digits than its factorization.

66136785491 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1935.

The product of its digits is 6531840, while the sum is 56.

The spelling of 66136785491 in words is "sixty-six billion, one hundred thirty-six million, seven hundred eighty-five thousand, four hundred ninety-one".