21649893408 has 192 divisors, whose sum is σ = 74185372800. Its totient is φ = 6055879680.

The previous prime is 21649893407. The next prime is 21649893413. The reversal of 21649893408 is 80439894612.

21649893408 is a `hidden beast` number, since 2 + 1 + 64 + 98 + 93 + 408 = 666.

It is a Harshad number since it is a multiple of its sum of digits (54).

It is not an unprimeable number, because it can be changed into a prime (21649893407) 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 31 ways as a sum of consecutive naturals, for example, 35938 + ... + 211166.

It is an arithmetic number, because the mean of its divisors is an integer number (386382150).

Almost surely, 2^21649893408 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 21649893408, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (37092686400).

21649893408 is an abundant number, since it is smaller than the sum of its proper divisors (52535479392).

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

21649893408 is a wasteful number, since it uses less digits than its factorization.

21649893408 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 175272 (or 175258 counting only the distinct ones).

The product of its (nonzero) digits is 2985984, while the sum is 54.

The spelling of 21649893408 in words is "twenty-one billion, six hundred forty-nine million, eight hundred ninety-three thousand, four hundred eight".