7871721909197 has 8 divisors (see below), whose sum is σ = 7894166374776. Its totient is φ = 7849284613632.

The previous prime is 7871721909173. The next prime is 7871721909211. The reversal of 7871721909197 is 7919091271787.

It can be written as a sum of positive squares in 4 ways, for example, as 630100976521 + 7241620932676 = 793789^2 + 2691026^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 7871721909197 - 2¹² = 7871721905101 is a prime.

It is a super-3 number, since 3×7871721909197³ (a number of 40 digits) contains 333 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (7871721909127) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 410213 + ... + 3988949.

It is an arithmetic number, because the mean of its divisors is an integer number (986770796847).

Almost surely, 2^{7871721909197} is an apocalyptic number.

It is an amenable number.

7871721909197 is a deficient number, since it is larger than the sum of its proper divisors (22444465579).

7871721909197 is a wasteful number, since it uses less digits than its factorization.

7871721909197 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3585007.

The product of its (nonzero) digits is 28005264, while the sum is 68.

The spelling of 7871721909197 in words is "seven trillion, eight hundred seventy-one billion, seven hundred twenty-one million, nine hundred nine thousand, one hundred ninety-seven".