642602161 has 4 divisors (see below), whose sum is σ = 649822500. Its totient is φ = 635381824.

The previous prime is 642602141. The next prime is 642602171. The reversal of 642602161 is 161206246.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 161206246 = 2 ⋅80603123.

It can be written as a sum of positive squares in 2 ways, for example, as 265038400 + 377563761 = 16280^2 + 19431^2 .

It is a cyclic number.

It is not a de Polignac number, because 642602161 - 2¹³ = 642593969 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (642602101) 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, 3610036 + ... + 3610213.

It is an arithmetic number, because the mean of its divisors is an integer number (162455625).

Almost surely, 2^642602161 is an apocalyptic number.

It is an amenable number.

642602161 is a deficient number, since it is larger than the sum of its proper divisors (7220339).

642602161 is an equidigital number, since it uses as much as digits as its factorization.

642602161 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7220338.

The product of its (nonzero) digits is 3456, while the sum is 28.

The square root of 642602161 is about 25349.5988331177. The cubic root of 642602161 is about 862.9402520593.

The spelling of 642602161 in words is "six hundred forty-two million, six hundred two thousand, one hundred sixty-one".