642404521 has 8 divisors (see below), whose sum is σ = 710676288. Its totient is φ = 575778000.

The previous prime is 642404501. The next prime is 642404531. The reversal of 642404521 is 125404246.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 642404521 - 2⁷ = 642404393 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 642404521.

It is not an unprimeable number, because it can be changed into a prime (642404501) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 410490 + ... + 412051.

It is an arithmetic number, because the mean of its divisors is an integer number (88834536).

Almost surely, 2^642404521 is an apocalyptic number.

It is an amenable number.

642404521 is a deficient number, since it is larger than the sum of its proper divisors (68271767).

642404521 is a wasteful number, since it uses less digits than its factorization.

642404521 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 822623.

The product of its (nonzero) digits is 7680, while the sum is 28.

The square root of 642404521 is about 25345.7002467874. The cubic root of 642404521 is about 862.8517737806.

Adding to 642404521 its reverse (125404246), we get a palindrome (767808767).

The spelling of 642404521 in words is "six hundred forty-two million, four hundred four thousand, five hundred twenty-one".