642869821 has 8 divisors (see below), whose sum is σ = 702000000. Its totient is φ = 583854240.

The previous prime is 642869819. The next prime is 642869831. The reversal of 642869821 is 128968246.

642869821 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

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

It is a cyclic number.

It is not a de Polignac number, because 642869821 - 2¹ = 642869819 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (642869831) 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, 16696 + ... + 39553.

It is an arithmetic number, because the mean of its divisors is an integer number (87750000).

Almost surely, 2^642869821 is an apocalyptic number.

It is an amenable number.

642869821 is a deficient number, since it is larger than the sum of its proper divisors (59130179).

642869821 is a wasteful number, since it uses less digits than its factorization.

642869821 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 57299.

The product of its digits is 331776, while the sum is 46.

The square root of 642869821 is about 25354.8776569716. The cubic root of 642869821 is about 863.0600475515.

The spelling of 642869821 in words is "six hundred forty-two million, eight hundred sixty-nine thousand, eight hundred twenty-one".