642126517 has 4 divisors (see below), whose sum is σ = 648746476. Its totient is φ = 635506560.

The previous prime is 642126509. The next prime is 642126539. The reversal of 642126517 is 715621246.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 165533956 + 476592561 = 12866^2 + 21831^2 .

It is a cyclic number.

It is not a de Polignac number, because 642126517 - 2³ = 642126509 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (642126547) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3309834 + ... + 3310027.

It is an arithmetic number, because the mean of its divisors is an integer number (162186619).

Almost surely, 2^642126517 is an apocalyptic number.

It is an amenable number.

642126517 is a deficient number, since it is larger than the sum of its proper divisors (6619959).

642126517 is an equidigital number, since it uses as much as digits as its factorization.

642126517 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6619958.

The product of its digits is 20160, while the sum is 34.

The square root of 642126517 is about 25340.2154095027. The cubic root of 642126517 is about 862.7272879114.

The spelling of 642126517 in words is "six hundred forty-two million, one hundred twenty-six thousand, five hundred seventeen".