643097971 has 2 divisors, whose sum is σ = 643097972. Its totient is φ = 643097970.

The previous prime is 643097969. The next prime is 643097989. The reversal of 643097971 is 179790346.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 643097971 - 2¹ = 643097969 is a prime.

Together with 643097969, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (643097911) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 321548985 + 321548986.

It is an arithmetic number, because the mean of its divisors is an integer number (321548986).

Almost surely, 2^643097971 is an apocalyptic number.

643097971 is a deficient number, since it is larger than the sum of its proper divisors (1).

643097971 is an equidigital number, since it uses as much as digits as its factorization.

643097971 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 285768, while the sum is 46.

The square root of 643097971 is about 25359.3763921749. The cubic root of 643097971 is about 863.1621334660.

It can be divided in two parts, 6430 and 97971, that added together give a palindrome (104401).

The spelling of 643097971 in words is "six hundred forty-three million, ninety-seven thousand, nine hundred seventy-one".