642220042 has 4 divisors (see below), whose sum is σ = 963330066. Its totient is φ = 321110020.

The previous prime is 642220039. The next prime is 642220057. The reversal of 642220042 is 240022246.

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

It can be written as a sum of positive squares in only one way, i.e., 437186281 + 205033761 = 20909^2 + 14319^2 .

It is a junction number, because it is equal to n+sod(n) for n = 642219995 and 642220022.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 160555009 + ... + 160555012.

Almost surely, 2^642220042 is an apocalyptic number.

642220042 is a deficient number, since it is larger than the sum of its proper divisors (321110024).

642220042 is a wasteful number, since it uses less digits than its factorization.

642220042 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 321110023.

The product of its (nonzero) digits is 1536, while the sum is 22.

The square root of 642220042 is about 25342.0607291514. The cubic root of 642220042 is about 862.7691709622.

Adding to 642220042 its reverse (240022246), we get a palindrome (882242288).

The spelling of 642220042 in words is "six hundred forty-two million, two hundred twenty thousand, forty-two".