643632770381 has 2 divisors, whose sum is σ = 643632770382. Its totient is φ = 643632770380.

The previous prime is 643632770371. The next prime is 643632770437. The reversal of 643632770381 is 183077236346.

643632770381 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., 640694588356 + 2938182025 = 800434^2 + 54205^2 .

It is a cyclic number.

It is not a de Polignac number, because 643632770381 - 2¹⁸ = 643632508237 is a prime.

It is a super-2 number, since 2×643632770381² (a number of 24 digits) contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (643632770371) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 321816385190 + 321816385191.

It is an arithmetic number, because the mean of its divisors is an integer number (321816385191).

Almost surely, 2^643632770381 is an apocalyptic number.

It is an amenable number.

643632770381 is a deficient number, since it is larger than the sum of its proper divisors (1).

643632770381 is an equidigital number, since it uses as much as digits as its factorization.

643632770381 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 3048192, while the sum is 50.

The spelling of 643632770381 in words is "six hundred forty-three billion, six hundred thirty-two million, seven hundred seventy thousand, three hundred eighty-one".