642421 has 4 divisors (see below), whose sum is σ = 691852. Its totient is φ = 592992.

The previous prime is 642419. The next prime is 642427. The reversal of 642421 is 124246.

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 378225 + 264196 = 615^2 + 514^2 .

It is a cyclic number.

It is not a de Polignac number, because 642421 - 2¹ = 642419 is a prime.

It is a Duffinian number.

It is a nialpdrome in base 15.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (642427) 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, 24696 + ... + 24721.

It is an arithmetic number, because the mean of its divisors is an integer number (172963).

2⁶⁴²⁴²¹ is an apocalyptic number.

It is an amenable number.

642421 is a deficient number, since it is larger than the sum of its proper divisors (49431).

642421 is a wasteful number, since it uses less digits than its factorization.

642421 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 49430.

The product of its digits is 384, while the sum is 19.

The square root of 642421 is about 801.5116967331. The cubic root of 642421 is about 86.2859151693.

Adding to 642421 its reverse (124246), we get a palindrome (766667).

It can be divided in two parts, 64 and 2421, that added together give a triangular number (2485 = T₇₀).

The spelling of 642421 in words is "six hundred forty-two thousand, four hundred twenty-one".