642767638 has 4 divisors (see below), whose sum is σ = 964151460. Its totient is φ = 321383818.

The previous prime is 642767627. The next prime is 642767639. The reversal of 642767638 is 836767246.

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

It is a junction number, because it is equal to n+sod(n) for n = 642767591 and 642767600.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (642767639) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 160691908 + ... + 160691911.

It is an arithmetic number, because the mean of its divisors is an integer number (241037865).

Almost surely, 2^642767638 is an apocalyptic number.

642767638 is a deficient number, since it is larger than the sum of its proper divisors (321383822).

642767638 is a wasteful number, since it uses less digits than its factorization.

642767638 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 321383821.

The product of its digits is 2032128, while the sum is 49.

The square root of 642767638 is about 25352.8625208279. The cubic root of 642767638 is about 863.0143178486.

The spelling of 642767638 in words is "six hundred forty-two million, seven hundred sixty-seven thousand, six hundred thirty-eight".