642905 has 8 divisors (see below), whose sum is σ = 782784. Its totient is φ = 506800.

The previous prime is 642899. The next prime is 642907. The reversal of 642905 is 509246.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 642905 - 2¹⁰ = 641881 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a nialpdrome in base 15.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 642905.

It is not an unprimeable number, because it can be changed into a prime (642907) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 551 + ... + 1260.

It is an arithmetic number, because the mean of its divisors is an integer number (97848).

2⁶⁴²⁹⁰⁵ is an apocalyptic number.

It is an amenable number.

642905 is a deficient number, since it is larger than the sum of its proper divisors (139879).

642905 is a wasteful number, since it uses less digits than its factorization.

642905 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1887.

The product of its (nonzero) digits is 2160, while the sum is 26.

The square root of 642905 is about 801.8135693539. The cubic root of 642905 is about 86.3075790000.

The spelling of 642905 in words is "six hundred forty-two thousand, nine hundred five".