642100621 has 2 divisors, whose sum is σ = 642100622. Its totient is φ = 642100620.

The previous prime is 642100619. The next prime is 642100633. The reversal of 642100621 is 126001246.

642100621 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 387538596 + 254562025 = 19686^2 + 15955^2 .

It is a cyclic number.

It is not a de Polignac number, because 642100621 - 2¹ = 642100619 is a prime.

Together with 642100619, it forms a pair of twin primes.

It is a junction number, because it is equal to n+sod(n) for n = 642100592 and 642100601.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (642100601) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 321050310 + 321050311.

It is an arithmetic number, because the mean of its divisors is an integer number (321050311).

Almost surely, 2^642100621 is an apocalyptic number.

It is an amenable number.

642100621 is a deficient number, since it is larger than the sum of its proper divisors (1).

642100621 is an equidigital number, since it uses as much as digits as its factorization.

642100621 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 576, while the sum is 22.

The square root of 642100621 is about 25339.7044378975. The cubic root of 642100621 is about 862.7156902560.

Adding to 642100621 its reverse (126001246), we get a palindrome (768101867).

The spelling of 642100621 in words is "six hundred forty-two million, one hundred thousand, six hundred twenty-one".