21036641664 has 128 divisors (see below), whose sum is σ = 57902837760. Its totient is φ = 6759936000.

The previous prime is 21036641663. The next prime is 21036641677. The reversal of 21036641664 is 46614663012.

It is a tau number, because it is divible by the number of its divisors (128).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21036641663) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 3222724 + ... + 3229244.

It is an arithmetic number, because the mean of its divisors is an integer number (452365920).

Almost surely, 2^21036641664 is an apocalyptic number.

21036641664 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 21036641664, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (28951418880).

21036641664 is an abundant number, since it is smaller than the sum of its proper divisors (36866196096).

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

21036641664 is a wasteful number, since it uses less digits than its factorization.

21036641664 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6840 (or 6828 counting only the distinct ones).

The product of its (nonzero) digits is 124416, while the sum is 39.

The spelling of 21036641664 in words is "twenty-one billion, thirty-six million, six hundred forty-one thousand, six hundred sixty-four".