681667766187 has 16 divisors (see below), whose sum is σ = 909652300800. Its totient is φ = 454064364000.

The previous prime is 681667766183. The next prime is 681667766191. The reversal of 681667766187 is 781667766186.

It is an interprime number because it is at equal distance from previous prime (681667766183) and next prime (681667766191).

It is not a de Polignac number, because 681667766187 - 2² = 681667766183 is a prime.

It is not an unprimeable number, because it can be changed into a prime (681667766183) 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, 19713189 + ... + 19747737.

It is an arithmetic number, because the mean of its divisors is an integer number (56853268800).

Almost surely, 2^681667766187 is an apocalyptic number.

681667766187 is a deficient number, since it is larger than the sum of its proper divisors (227984534613).

681667766187 is a wasteful number, since it uses less digits than its factorization.

681667766187 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 39874.

The product of its digits is 170698752, while the sum is 69.

Subtracting 681667766187 from its reverse (781667766186), we obtain a palindrome (99999999999).

The spelling of 681667766187 in words is "six hundred eighty-one billion, six hundred sixty-seven million, seven hundred sixty-six thousand, one hundred eighty-seven".