642864 has 40 divisors (see below), whose sum is σ = 1696320. Its totient is φ = 209728.

The previous prime is 642853. The next prime is 642869. The reversal of 642864 is 468246.

642864 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a hoax number, since the sum of its digits (30) coincides with the sum of the digits of its distinct prime factors.

It is a nude number because it is divisible by every one of its digits.

It is not an unprimeable number, because it can be changed into a prime (642869) by changing a digit.

642864 is an untouchable number, because it is not equal to the sum of proper divisors of any number.

It is an upside-down number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 2719 + ... + 2945.

It is an arithmetic number, because the mean of its divisors is an integer number (42408).

2⁶⁴²⁸⁶⁴ is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 642864, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (848160).

642864 is an abundant number, since it is smaller than the sum of its proper divisors (1053456).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

642864 is a wasteful number, since it uses less digits than its factorization.

642864 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 297 (or 291 counting only the distinct ones).

The product of its digits is 9216, while the sum is 30.

The square root of 642864 is about 801.7880019057. The cubic root of 642864 is about 86.3057442624.

The spelling of 642864 in words is "six hundred forty-two thousand, eight hundred sixty-four".