643340121605 has 16 divisors (see below), whose sum is σ = 852960409344. Its totient is φ = 463336515840.

The previous prime is 643340121587. The next prime is 643340121629. The reversal of 643340121605 is 506121043346.

It is not a de Polignac number, because 643340121605 - 2²⁶ = 643273012741 is a prime.

It is a Duffinian number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 164535161 + ... + 164539070.

It is an arithmetic number, because the mean of its divisors is an integer number (53310025584).

Almost surely, 2^643340121605 is an apocalyptic number.

It is an amenable number.

643340121605 is a deficient number, since it is larger than the sum of its proper divisors (209620287739).

643340121605 is a wasteful number, since it uses less digits than its factorization.

643340121605 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 329074276.

The product of its (nonzero) digits is 51840, while the sum is 35.

The spelling of 643340121605 in words is "six hundred forty-three billion, three hundred forty million, one hundred twenty-one thousand, six hundred five".