13721831961 has 4 divisors (see below), whose sum is σ = 18295775952. Its totient is φ = 9147887972.

The previous prime is 13721831923. The next prime is 13721831987. The reversal of 13721831961 is 16913812731.

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, and also an emirpimes, since its reverse is a distinct semiprime: 16913812731 = 3 ⋅5637937577.

It is a cyclic number.

It is not a de Polignac number, because 13721831961 - 2¹⁰ = 13721830937 is a prime.

It is a super-2 number, since 2×13721831961² (a number of 21 digits) contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (13721831261) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2286971991 + ... + 2286971996.

It is an arithmetic number, because the mean of its divisors is an integer number (4573943988).

Almost surely, 2^13721831961 is an apocalyptic number.

It is an amenable number.

13721831961 is a deficient number, since it is larger than the sum of its proper divisors (4573943991).

13721831961 is an equidigital number, since it uses as much as digits as its factorization.

13721831961 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4573943990.

The product of its digits is 54432, while the sum is 42.

The spelling of 13721831961 in words is "thirteen billion, seven hundred twenty-one million, eight hundred thirty-one thousand, nine hundred sixty-one".