642162581 has 4 divisors (see below), whose sum is σ = 642229164. Its totient is φ = 642096000.

The previous prime is 642162571. The next prime is 642162637. The reversal of 642162581 is 185261246.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It can be written as a sum of positive squares in 2 ways, for example, as 241802500 + 400360081 = 15550^2 + 20009^2 .

It is a cyclic number.

It is not a de Polignac number, because 642162581 - 2⁶ = 642162517 is a prime.

It is a super-2 number, since 2×642162581² = 824745560873163122, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (642162571) 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, 15740 + ... + 39141.

It is an arithmetic number, because the mean of its divisors is an integer number (160557291).

Almost surely, 2^642162581 is an apocalyptic number.

It is an amenable number.

642162581 is a deficient number, since it is larger than the sum of its proper divisors (66583).

642162581 is a wasteful number, since it uses less digits than its factorization.

642162581 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 66582.

The product of its digits is 23040, while the sum is 35.

The square root of 642162581 is about 25340.9269956724. The cubic root of 642162581 is about 862.7434388379.

The spelling of 642162581 in words is "six hundred forty-two million, one hundred sixty-two thousand, five hundred eighty-one".