642689478 has 80 divisors (see below), whose sum is σ = 1542024000. Its totient is φ = 199458288.

The previous prime is 642689477. The next prime is 642689479. The reversal of 642689478 is 874986246.

642689478 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is an interprime number because it is at equal distance from previous prime (642689477) and next prime (642689479).

It is a Harshad number since it is a multiple of its sum of digits (54).

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (642689477) by changing a digit.

It is a polite number, since it can be written in 39 ways as a sum of consecutive naturals, for example, 179833 + ... + 183371.

It is an arithmetic number, because the mean of its divisors is an integer number (19275300).

Almost surely, 2^642689478 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 642689478, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (771012000).

642689478 is an abundant number, since it is smaller than the sum of its proper divisors (899334522).

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

642689478 is a wasteful number, since it uses less digits than its factorization.

642689478 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3631 (or 3622 counting only the distinct ones).

The product of its digits is 4644864, while the sum is 54.

The square root of 642689478 is about 25351.3210306682. The cubic root of 642689478 is about 862.9793358274.

The spelling of 642689478 in words is "six hundred forty-two million, six hundred eighty-nine thousand, four hundred seventy-eight".