642099649 has 2 divisors, whose sum is σ = 642099650. Its totient is φ = 642099648.

The previous prime is 642099629. The next prime is 642099697. The reversal of 642099649 is 946990246.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 635040000 + 7059649 = 25200^2 + 2657^2 .

It is a cyclic number.

It is not a de Polignac number, because 642099649 - 2⁹ = 642099137 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (642099629) 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, 321049824 + 321049825.

It is an arithmetic number, because the mean of its divisors is an integer number (321049825).

Almost surely, 2^642099649 is an apocalyptic number.

It is an amenable number.

642099649 is a deficient number, since it is larger than the sum of its proper divisors (1).

642099649 is an equidigital number, since it uses as much as digits as its factorization.

642099649 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 839808, while the sum is 49.

The square root of 642099649 is about 25339.6852585031. The cubic root of 642099649 is about 862.7152549348.

The spelling of 642099649 in words is "six hundred forty-two million, ninety-nine thousand, six hundred forty-nine".