64839978 has 48 divisors (see below), whose sum is σ = 163987200. Its totient is φ = 18129888.

The previous prime is 64839949. The next prime is 64839979. The reversal of 64839978 is 87993846.

64839978 is a `hidden beast` number, since 6 + 483 + 99 + 78 = 666.

It is not an unprimeable number, because it can be changed into a prime (64839979) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 448 + ... + 11396.

It is an arithmetic number, because the mean of its divisors is an integer number (3416400).

Almost surely, 2^64839978 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 64839978, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (81993600).

64839978 is an abundant number, since it is smaller than the sum of its proper divisors (99147222).

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

64839978 is a wasteful number, since it uses less digits than its factorization.

64839978 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 11011 (or 11008 counting only the distinct ones).

The product of its digits is 2612736, while the sum is 54.

The square root of 64839978 is about 8052.3274896144. The cubic root of 64839978 is about 401.7423536564.

It can be divided in two parts, 6483 and 9978, that added together give a palindrome (16461).

The spelling of 64839978 in words is "sixty-four million, eight hundred thirty-nine thousand, nine hundred seventy-eight".