993897766681 has 4 divisors (see below), whose sum is σ = 1010743491600. Its totient is φ = 977052041764.

The previous prime is 993897766657. The next prime is 993897766691. The reversal of 993897766681 is 186667798399.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 993897766681 - 2³⁷ = 856458813209 is a prime.

It is a super-2 number, since 2×993897766681² (a number of 25 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (993897766651) 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 3 ways as a sum of consecutive naturals, for example, 8422862371 + ... + 8422862488.

It is an arithmetic number, because the mean of its divisors is an integer number (252685872900).

Almost surely, 2^993897766681 is an apocalyptic number.

It is an amenable number.

993897766681 is a deficient number, since it is larger than the sum of its proper divisors (16845724919).

993897766681 is a wasteful number, since it uses less digits than its factorization.

993897766681 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 16845724918.

The product of its digits is 1481421312, while the sum is 79.

The spelling of 993897766681 in words is "nine hundred ninety-three billion, eight hundred ninety-seven million, seven hundred sixty-six thousand, six hundred eighty-one".