64812121920 has 1344 divisors, whose sum is σ = 300400151040. Its totient is φ = 12835749888.

The previous prime is 64812121873. The next prime is 64812121961. The reversal of 64812121920 is 2912121846.

64812121920 is a `hidden beast` number, since 648 + 1 + 2 + 1 + 2 + 1 + 9 + 2 + 0 = 666.

It is a tau number, because it is divible by the number of its divisors (1344).

It is a super-2 number, since 2×64812121920² (a number of 22 digits) contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 191 ways as a sum of consecutive naturals, for example, 173758854 + ... + 173759226.

Almost surely, 2^64812121920 is an apocalyptic number.

64812121920 is a gapful number since it is divisible by the number (60) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 64812121920, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (150200075520).

64812121920 is an abundant number, since it is smaller than the sum of its proper divisors (235588029120).

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

64812121920 is a wasteful number, since it uses less digits than its factorization.

64812121920 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 449 (or 420 counting only the distinct ones).

The product of its (nonzero) digits is 13824, while the sum is 36.

The spelling of 64812121920 in words is "sixty-four billion, eight hundred twelve million, one hundred twenty-one thousand, nine hundred twenty".