642636405 has 48 divisors (see below), whose sum is σ = 1142429184. Its totient is φ = 334026240.

The previous prime is 642636391. The next prime is 642636439. The reversal of 642636405 is 504636246.

642636405 is a `hidden beast` number, since 6 + 4 + 2 + 6 + 3 + 640 + 5 = 666.

It is not a de Polignac number, because 642636405 - 2⁴ = 642636389 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 642636405.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 657277 + ... + 658253.

It is an arithmetic number, because the mean of its divisors is an integer number (23800608).

Almost surely, 2^642636405 is an apocalyptic number.

It is an amenable number.

642636405 is a deficient number, since it is larger than the sum of its proper divisors (499792779).

642636405 is a wasteful number, since it uses less digits than its factorization.

642636405 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1346 (or 1343 counting only the distinct ones).

The product of its (nonzero) digits is 103680, while the sum is 36.

The square root of 642636405 is about 25350.2742588714. The cubic root of 642636405 is about 862.9555803619.

The spelling of 642636405 in words is "six hundred forty-two million, six hundred thirty-six thousand, four hundred five".