665121972801 has 32 divisors (see below), whose sum is σ = 1041922344960. Its totient is φ = 372077294400.

The previous prime is 665121972797. The next prime is 665121972803. The reversal of 665121972801 is 108279121566.

It is a happy number.

665121972801 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is not a de Polignac number, because 665121972801 - 2² = 665121972797 is a prime.

It is not an unprimeable number, because it can be changed into a prime (665121972803) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 16226190 + ... + 16267128.

It is an arithmetic number, because the mean of its divisors is an integer number (32560073280).

Almost surely, 2^665121972801 is an apocalyptic number.

It is an amenable number.

665121972801 is a deficient number, since it is larger than the sum of its proper divisors (376800372159).

665121972801 is a wasteful number, since it uses less digits than its factorization.

665121972801 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 78837.

The product of its (nonzero) digits is 362880, while the sum is 48.

The spelling of 665121972801 in words is "six hundred sixty-five billion, one hundred twenty-one million, nine hundred seventy-two thousand, eight hundred one".