21040164864 has 156 divisors (see below), whose sum is σ = 61387875432. Its totient is φ = 6942720000.

The previous prime is 21040164863. The next prime is 21040164889. The reversal of 21040164864 is 46846104012.

It is a happy number.

21040164864 is a `hidden beast` number, since 2 + 1 + 0 + 4 + 0 + 1 + 648 + 6 + 4 = 666.

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

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21040164863) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 3720439 + ... + 3726089.

It is an arithmetic number, because the mean of its divisors is an integer number (393512022).

Almost surely, 2^21040164864 is an apocalyptic number.

21040164864 is a gapful number since it is divisible by the number (24) 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 21040164864, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (30693937716).

21040164864 is an abundant number, since it is smaller than the sum of its proper divisors (40347710568).

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

21040164864 is a wasteful number, since it uses less digits than its factorization.

21040164864 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5782 (or 5757 counting only the distinct ones).

The product of its (nonzero) digits is 36864, while the sum is 36.

Adding to 21040164864 its reverse (46846104012), we get a palindrome (67886268876).

The spelling of 21040164864 in words is "twenty-one billion, forty million, one hundred sixty-four thousand, eight hundred sixty-four".