642440531 has 4 divisors (see below), whose sum is σ = 670372752. Its totient is φ = 614508312.

The previous prime is 642440503. The next prime is 642440569. The reversal of 642440531 is 135044246.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 642440531 - 2¹⁴ = 642424147 is a prime.

It is a super-2 number, since 2×642440531² = 825459671743123922, which contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 642440494 and 642440503.

It is not an unprimeable number, because it can be changed into a prime (642440581) 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, 13966076 + ... + 13966121.

It is an arithmetic number, because the mean of its divisors is an integer number (167593188).

Almost surely, 2^642440531 is an apocalyptic number.

642440531 is a deficient number, since it is larger than the sum of its proper divisors (27932221).

642440531 is a wasteful number, since it uses less digits than its factorization.

642440531 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 27932220.

The product of its (nonzero) digits is 11520, while the sum is 29.

The square root of 642440531 is about 25346.4106137339. The cubic root of 642440531 is about 862.8678958712.

Adding to 642440531 its reverse (135044246), we get a palindrome (777484777).

The spelling of 642440531 in words is "six hundred forty-two million, four hundred forty thousand, five hundred thirty-one".