642543309405 has 12 divisors (see below), whose sum is σ = 1113741736380. Its totient is φ = 342689764992.

The previous prime is 642543309391. The next prime is 642543309481. The reversal of 642543309405 is 504903345246.

642543309405 is a `hidden beast` number, since 64 + 2 + 543 + 3 + 0 + 9 + 40 + 5 = 666.

It can be written as a sum of positive squares in 2 ways, for example, as 87300748089 + 555242561316 = 295467^2 + 745146^2 .

It is not a de Polignac number, because 642543309405 - 2¹⁵ = 642543276637 is a prime.

It is a super-2 number, since 2×642543309405² (a number of 24 digits) contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (45), and also a Moran number because the ratio is a prime number: 14278740209 = 642543309405 / (6 + 4 + 2 + 5 + 4 + 3 + 3 + 0 + 9 + 4 + 0 + 5).

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 7139370060 + ... + 7139370149.

It is an arithmetic number, because the mean of its divisors is an integer number (92811811365).

Almost surely, 2^642543309405 is an apocalyptic number.

It is an amenable number.

642543309405 is a deficient number, since it is larger than the sum of its proper divisors (471198426975).

642543309405 is a wasteful number, since it uses less digits than its factorization.

642543309405 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 14278740220 (or 14278740217 counting only the distinct ones).

The product of its (nonzero) digits is 1555200, while the sum is 45.

The spelling of 642543309405 in words is "six hundred forty-two billion, five hundred forty-three million, three hundred nine thousand, four hundred five".