642510762821 has 2 divisors, whose sum is σ = 642510762822. Its totient is φ = 642510762820.

The previous prime is 642510762743. The next prime is 642510762847. The reversal of 642510762821 is 128267015246.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 373704806596 + 268805956225 = 611314^2 + 518465^2 .

It is a cyclic number.

It is not a de Polignac number, because 642510762821 - 2¹⁰ = 642510761797 is a prime.

It is a Sophie Germain prime.

It is a Curzon number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (642510762521) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 321255381410 + 321255381411.

It is an arithmetic number, because the mean of its divisors is an integer number (321255381411).

Almost surely, 2^642510762821 is an apocalyptic number.

It is an amenable number.

642510762821 is a deficient number, since it is larger than the sum of its proper divisors (1).

642510762821 is an equidigital number, since it uses as much as digits as its factorization.

642510762821 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 322560, while the sum is 44.

The spelling of 642510762821 in words is "six hundred forty-two billion, five hundred ten million, seven hundred sixty-two thousand, eight hundred twenty-one".