642222101 has 2 divisors, whose sum is σ = 642222102. Its totient is φ = 642222100.

The previous prime is 642222089. The next prime is 642222103. The reversal of 642222101 is 101222246.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 562923076 + 79299025 = 23726^2 + 8905^2 .

It is a cyclic number.

It is not a de Polignac number, because 642222101 - 2⁶ = 642222037 is a prime.

Together with 642222103, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (642222103) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 321111050 + 321111051.

It is an arithmetic number, because the mean of its divisors is an integer number (321111051).

Almost surely, 2^642222101 is an apocalyptic number.

It is an amenable number.

642222101 is a deficient number, since it is larger than the sum of its proper divisors (1).

642222101 is an equidigital number, since it uses as much as digits as its factorization.

642222101 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 384, while the sum is 20.

The square root of 642222101 is about 25342.1013532817. The cubic root of 642222101 is about 862.7700929929.

Adding to 642222101 its reverse (101222246), we get a palindrome (743444347).

The spelling of 642222101 in words is "six hundred forty-two million, two hundred twenty-two thousand, one hundred one".