64881920 has 72 divisors (see below), whose sum is σ = 156844296. Its totient is φ = 25714688.

The previous prime is 64881917. The next prime is 64881931. The reversal of 64881920 is 2918846.

It can be written as a sum of positive squares in 4 ways, for example, as 35808256 + 29073664 = 5984^2 + 5392^2 .

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 221294 + ... + 221586.

It is an arithmetic number, because the mean of its divisors is an integer number (2178393).

Almost surely, 2^64881920 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 64881920, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (78422148).

64881920 is an abundant number, since it is smaller than the sum of its proper divisors (91962376).

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

64881920 is a wasteful number, since it uses less digits than its factorization.

64881920 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 487 (or 473 counting only the distinct ones).

The product of its (nonzero) digits is 27648, while the sum is 38.

The square root of 64881920 is about 8054.9314087707. The cubic root of 64881920 is about 401.8289578702.

The spelling of 64881920 in words is "sixty-four million, eight hundred eighty-one thousand, nine hundred twenty".