21905019864 has 640 divisors, whose sum is σ = 81494138880. Its totient is φ = 5337446400.

The previous prime is 21905019823. The next prime is 21905019901. The reversal of 21905019864 is 46891050912.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 159 ways as a sum of consecutive naturals, for example, 42043924 + ... + 42044444.

It is an arithmetic number, because the mean of its divisors is an integer number (127334592).

Almost surely, 2^21905019864 is an apocalyptic number.

21905019864 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 21905019864, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (40747069440).

21905019864 is an abundant number, since it is smaller than the sum of its proper divisors (59589119016).

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

21905019864 is a wasteful number, since it uses less digits than its factorization.

21905019864 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 613 (or 600 counting only the distinct ones).

The product of its (nonzero) digits is 155520, while the sum is 45.

The spelling of 21905019864 in words is "twenty-one billion, nine hundred five million, nineteen thousand, eight hundred sixty-four".