642525509 has 4 divisors (see below), whose sum is σ = 642768204. Its totient is φ = 642282816.

The previous prime is 642525491. The next prime is 642525529. The reversal of 642525509 is 905525246.

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 117657409 + 524868100 = 10847^2 + 22910^2 .

It is a cyclic number.

It is not a de Polignac number, because 642525509 - 2⁸ = 642525253 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (642525529) 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, 117332 + ... + 122685.

It is an arithmetic number, because the mean of its divisors is an integer number (160692051).

Almost surely, 2^642525509 is an apocalyptic number.

It is an amenable number.

642525509 is a deficient number, since it is larger than the sum of its proper divisors (242695).

642525509 is a wasteful number, since it uses less digits than its factorization.

642525509 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 242694.

The product of its (nonzero) digits is 108000, while the sum is 38.

The square root of 642525509 is about 25348.0868903355. The cubic root of 642525509 is about 862.9059391099.

The spelling of 642525509 in words is "six hundred forty-two million, five hundred twenty-five thousand, five hundred nine".