681609162720021 has 16 divisors (see below), whose sum is σ = 948469980441984. Its totient is φ = 434583234607104.

The previous prime is 681609162719939. The next prime is 681609162720077. The reversal of 681609162720021 is 120027261906186.

It is not a de Polignac number, because 681609162720021 - 2¹⁵ = 681609162687253 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (681609162721021) 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, 750526396 + ... + 751434021.

It is an arithmetic number, because the mean of its divisors is an integer number (59279373777624).

Almost surely, 2^{681609162720021} is an apocalyptic number.

It is an amenable number.

681609162720021 is a deficient number, since it is larger than the sum of its proper divisors (266860817721963).

681609162720021 is a wasteful number, since it uses less digits than its factorization.

681609162720021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1501967020.

The product of its (nonzero) digits is 870912, while the sum is 51.

The spelling of 681609162720021 in words is "six hundred eighty-one trillion, six hundred nine billion, one hundred sixty-two million, seven hundred twenty thousand, twenty-one".