642935521 has 4 divisors (see below), whose sum is σ = 644050372. Its totient is φ = 641820672.

The previous prime is 642935479. The next prime is 642935533. The reversal of 642935521 is 125539246.

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 633075921 + 9859600 = 25161^2 + 3140^2 .

It is a cyclic number.

It is not a de Polignac number, because 642935521 - 2²¹ = 640838369 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (642935561) 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, 556560 + ... + 557713.

It is an arithmetic number, because the mean of its divisors is an integer number (161012593).

Almost surely, 2^642935521 is an apocalyptic number.

It is an amenable number.

642935521 is a deficient number, since it is larger than the sum of its proper divisors (1114851).

642935521 is a wasteful number, since it uses less digits than its factorization.

642935521 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1114850.

The product of its digits is 64800, while the sum is 37.

The square root of 642935521 is about 25356.1732325680. The cubic root of 642935521 is about 863.0894475491.

The spelling of 642935521 in words is "six hundred forty-two million, nine hundred thirty-five thousand, five hundred twenty-one".