64821816 has 128 divisors (see below), whose sum is σ = 193536000. Its totient is φ = 20030976.

The previous prime is 64821781. The next prime is 64821821. The reversal of 64821816 is 61812846.

64821816 is a `hidden beast` number, since 648 + 2 + 1 + 8 + 1 + 6 = 666.

It is a hoax number, since the sum of its digits (36) coincides with the sum of the digits of its distinct prime factors.

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

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

Its product of digits (18432) is a multiple of the sum of its prime divisors (288).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 466275 + ... + 466413.

It is an arithmetic number, because the mean of its divisors is an integer number (1512000).

Almost surely, 2^64821816 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 64821816, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (96768000).

64821816 is an abundant number, since it is smaller than the sum of its proper divisors (128714184).

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

64821816 is a wasteful number, since it uses less digits than its factorization.

64821816 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 298 (or 288 counting only the distinct ones).

The product of its digits is 18432, while the sum is 36.

The square root of 64821816 is about 8051.1996621622. The cubic root of 64821816 is about 401.7048401438.

The spelling of 64821816 in words is "sixty-four million, eight hundred twenty-one thousand, eight hundred sixteen".