643019215977521 has 2 divisors, whose sum is σ = 643019215977522. Its totient is φ = 643019215977520.

The previous prime is 643019215977449. The next prime is 643019215977601. The reversal of 643019215977521 is 125779512910346.

643019215977521 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 610493170585600 + 32526045391921 = 24708160^2 + 5703161^2 .

It is a cyclic number.

It is not a de Polignac number, because 643019215977521 - 2¹⁸ = 643019215715377 is a prime.

It is not a weakly prime, because it can be changed into another prime (643019215977121) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 321509607988760 + 321509607988761.

It is an arithmetic number, because the mean of its divisors is an integer number (321509607988761).

Almost surely, 2^{643019215977521} is an apocalyptic number.

It is an amenable number.

643019215977521 is a deficient number, since it is larger than the sum of its proper divisors (1).

643019215977521 is an equidigital number, since it uses as much as digits as its factorization.

643019215977521 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 28576800, while the sum is 62.

The spelling of 643019215977521 in words is "six hundred forty-three trillion, nineteen billion, two hundred fifteen million, nine hundred seventy-seven thousand, five hundred twenty-one".