643958418431 has 2 divisors, whose sum is σ = 643958418432. Its totient is φ = 643958418430.

The previous prime is 643958418427. The next prime is 643958418437. The reversal of 643958418431 is 134814859346.

It is a happy number.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 643958418431 - 2² = 643958418427 is a prime.

It is a super-2 number, since 2×643958418431² (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 (643958418437) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 321979209215 + 321979209216.

It is an arithmetic number, because the mean of its divisors is an integer number (321979209216).

Almost surely, 2^643958418431 is an apocalyptic number.

643958418431 is a deficient number, since it is larger than the sum of its proper divisors (1).

643958418431 is an equidigital number, since it uses as much as digits as its factorization.

643958418431 is an evil number, because the sum of its binary digits is even.

The product of its digits is 9953280, while the sum is 56.

The spelling of 643958418431 in words is "six hundred forty-three billion, nine hundred fifty-eight million, four hundred eighteen thousand, four hundred thirty-one".