642689479 has 2 divisors, whose sum is σ = 642689480. Its totient is φ = 642689478.

The previous prime is 642689477. The next prime is 642689521. The reversal of 642689479 is 974986246.

It is a happy number.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 642689479 - 2¹ = 642689477 is a prime.

Together with 642689477, it forms a pair of twin primes.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (642689477) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 321344739 + 321344740.

It is an arithmetic number, because the mean of its divisors is an integer number (321344740).

Almost surely, 2^642689479 is an apocalyptic number.

642689479 is a deficient number, since it is larger than the sum of its proper divisors (1).

642689479 is an equidigital number, since it uses as much as digits as its factorization.

642689479 is an evil number, because the sum of its binary digits is even.

The product of its digits is 5225472, while the sum is 55.

The square root of 642689479 is about 25351.3210503910. The cubic root of 642689479 is about 862.9793362750.

The spelling of 642689479 in words is "six hundred forty-two million, six hundred eighty-nine thousand, four hundred seventy-nine".