816121311601 has 4 divisors (see below), whose sum is σ = 851604846912. Its totient is φ = 780637776292.

The previous prime is 816121311581. The next prime is 816121311619. The reversal of 816121311601 is 106113121618.

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 816121311601 - 2²⁵ = 816087757169 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (816121311671) 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, 17741767621 + ... + 17741767666.

It is an arithmetic number, because the mean of its divisors is an integer number (212901211728).

Almost surely, 2^816121311601 is an apocalyptic number.

It is an amenable number.

816121311601 is a deficient number, since it is larger than the sum of its proper divisors (35483535311).

816121311601 is a wasteful number, since it uses less digits than its factorization.

816121311601 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 35483535310.

The product of its (nonzero) digits is 1728, while the sum is 31.

The spelling of 816121311601 in words is "eight hundred sixteen billion, one hundred twenty-one million, three hundred eleven thousand, six hundred one".