642650505161 has 4 divisors (see below), whose sum is σ = 734457720192. Its totient is φ = 550843290132.

The previous prime is 642650505151. The next prime is 642650505197. The reversal of 642650505161 is 161505056246.

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: 161505056246 = 2 ⋅80752528123.

It is a cyclic number.

It is not a de Polignac number, because 642650505161 - 2¹⁰ = 642650504137 is a prime.

It is not an unprimeable number, because it can be changed into a prime (642650505151) 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, 45903607505 + ... + 45903607518.

It is an arithmetic number, because the mean of its divisors is an integer number (183614430048).

Almost surely, 2^642650505161 is an apocalyptic number.

It is an amenable number.

642650505161 is a deficient number, since it is larger than the sum of its proper divisors (91807215031).

642650505161 is an equidigital number, since it uses as much as digits as its factorization.

642650505161 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 91807215030.

The product of its (nonzero) digits is 216000, while the sum is 41.

The spelling of 642650505161 in words is "six hundred forty-two billion, six hundred fifty million, five hundred five thousand, one hundred sixty-one".