642609491 has 2 divisors, whose sum is σ = 642609492. Its totient is φ = 642609490.

The previous prime is 642609439. The next prime is 642609493. The reversal of 642609491 is 194906246.

642609491 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 642609491 - 2¹⁰ = 642608467 is a prime.

It is a Sophie Germain prime.

Together with 642609493, it forms a pair of twin primes.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (642609493) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 321304745 + 321304746.

It is an arithmetic number, because the mean of its divisors is an integer number (321304746).

Almost surely, 2^642609491 is an apocalyptic number.

642609491 is a deficient number, since it is larger than the sum of its proper divisors (1).

642609491 is an equidigital number, since it uses as much as digits as its factorization.

642609491 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 93312, while the sum is 41.

The square root of 642609491 is about 25349.7434109302. The cubic root of 642609491 is about 862.9435331605.

The spelling of 642609491 in words is "six hundred forty-two million, six hundred nine thousand, four hundred ninety-one".