642123331 has 4 divisors (see below), whose sum is σ = 642400200. Its totient is φ = 641846464.

The previous prime is 642123329. The next prime is 642123347. The reversal of 642123331 is 133321246.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 133321246 = 2 ⋅66660623.

It is a cyclic number.

It is not a de Polignac number, because 642123331 - 2¹ = 642123329 is a prime.

It is a super-2 number, since 2×642123331² = 824644744429071122, 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 = 642123296 and 642123305.

It is not an unprimeable number, because it can be changed into a prime (642123301) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 134926 + ... + 139603.

It is an arithmetic number, because the mean of its divisors is an integer number (160600050).

Almost surely, 2^642123331 is an apocalyptic number.

642123331 is a deficient number, since it is larger than the sum of its proper divisors (276869).

642123331 is a wasteful number, since it uses less digits than its factorization.

642123331 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 276868.

The product of its digits is 2592, while the sum is 25.

The square root of 642123331 is about 25340.1525449236. The cubic root of 642123331 is about 862.7258610619.

Adding to 642123331 its reverse (133321246), we get a palindrome (775444577).

The spelling of 642123331 in words is "six hundred forty-two million, one hundred twenty-three thousand, three hundred thirty-one".