21337841664 has 252 divisors, whose sum is σ = 64167590994. Its totient is φ = 7094697984.

The previous prime is 21337841621. The next prime is 21337841671. The reversal of 21337841664 is 46614873312.

21337841664 is a `hidden beast` number, since 213 + 378 + 4 + 1 + 6 + 64 = 666.

It can be written as a sum of positive squares in only one way, i.e., 16796160000 + 4541681664 = 129600^2 + 67392^2 .

It is an unprimeable number.

It is a polite number, since it can be written in 17 ways as a sum of consecutive naturals, for example, 53747514 + ... + 53747910.

Almost surely, 2^21337841664 is an apocalyptic number.

21337841664 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 21337841664, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (32083795497).

21337841664 is an abundant number, since it is smaller than the sum of its proper divisors (42829749330).

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

21337841664 is an frugal number, since it uses more digits than its factorization.

21337841664 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 447 (or 402 counting only the distinct ones).

The product of its digits is 580608, while the sum is 45.

The spelling of 21337841664 in words is "twenty-one billion, three hundred thirty-seven million, eight hundred forty-one thousand, six hundred sixty-four".