642235521 has 16 divisors (see below), whose sum is σ = 885265920. Its totient is φ = 413873280.

The previous prime is 642235519. The next prime is 642235523. The reversal of 642235521 is 125532246.

It is an interprime number because it is at equal distance from previous prime (642235519) and next prime (642235523).

It is not a de Polignac number, because 642235521 - 2¹ = 642235519 is a prime.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (642235523) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 10545 + ... + 37358.

It is an arithmetic number, because the mean of its divisors is an integer number (55329120).

Almost surely, 2^642235521 is an apocalyptic number.

It is an amenable number.

642235521 is a deficient number, since it is larger than the sum of its proper divisors (243030399).

642235521 is a wasteful number, since it uses less digits than its factorization.

642235521 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 48056.

The product of its digits is 14400, while the sum is 30.

The square root of 642235521 is about 25342.3661286787. The cubic root of 642235521 is about 862.7761024892.

Adding to 642235521 its reverse (125532246), we get a palindrome (767767767).

The spelling of 642235521 in words is "six hundred forty-two million, two hundred thirty-five thousand, five hundred twenty-one".