643654202551 has 2 divisors, whose sum is σ = 643654202552. Its totient is φ = 643654202550.

The previous prime is 643654202473. The next prime is 643654202593. The reversal of 643654202551 is 155202456346.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 643654202551 - 2¹⁹ = 643653678263 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 643654202498 and 643654202507.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (643654242551) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 321827101275 + 321827101276.

It is an arithmetic number, because the mean of its divisors is an integer number (321827101276).

Almost surely, 2^643654202551 is an apocalyptic number.

643654202551 is a deficient number, since it is larger than the sum of its proper divisors (1).

643654202551 is an equidigital number, since it uses as much as digits as its factorization.

643654202551 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 864000, while the sum is 43.

Adding to 643654202551 its reverse (155202456346), we get a palindrome (798856658897).

The spelling of 643654202551 in words is "six hundred forty-three billion, six hundred fifty-four million, two hundred two thousand, five hundred fifty-one".