642920009 has 2 divisors, whose sum is σ = 642920010. Its totient is φ = 642920008.

The previous prime is 642919999. The next prime is 642920011. The reversal of 642920009 is 900029246.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 352387984 + 290532025 = 18772^2 + 17045^2 .

It is a cyclic number.

It is not a de Polignac number, because 642920009 - 2⁴ = 642919993 is a prime.

It is a super-2 number, since 2×642920009² = 826692275945120162, which contains 22 as substring.

Together with 642920011, 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 (642920209) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 321460004 + 321460005.

It is an arithmetic number, because the mean of its divisors is an integer number (321460005).

Almost surely, 2^642920009 is an apocalyptic number.

It is an amenable number.

642920009 is a deficient number, since it is larger than the sum of its proper divisors (1).

642920009 is an equidigital number, since it uses as much as digits as its factorization.

642920009 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 7776, while the sum is 32.

The square root of 642920009 is about 25355.8673486040. The cubic root of 642920009 is about 863.0825062874.

The spelling of 642920009 in words is "six hundred forty-two million, nine hundred twenty thousand, nine".