643736869456 has 20 divisors (see below), whose sum is σ = 1249274853172. Its totient is φ = 321343358976.

The previous prime is 643736869429. The next prime is 643736869487. The reversal of 643736869456 is 654968637346.

It can be written as a sum of positive squares in 2 ways, for example, as 124126563856 + 519610305600 = 352316^2 + 720840^2 .

It is a super-2 number, since 2×643736869456² (a number of 24 digits) contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 643736869391 and 643736869400.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 32807121 + ... + 32826736.

Almost surely, 2^643736869456 is an apocalyptic number.

It is an amenable number.

643736869456 is a deficient number, since it is larger than the sum of its proper divisors (605537983716).

643736869456 is a wasteful number, since it uses less digits than its factorization.

643736869456 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 65634478 (or 65634472 counting only the distinct ones).

The product of its digits is 470292480, while the sum is 67.

The spelling of 643736869456 in words is "six hundred forty-three billion, seven hundred thirty-six million, eight hundred sixty-nine thousand, four hundred fifty-six".