21506378292 has 144 divisors (see below), whose sum is σ = 67389259392. Its totient is φ = 5642127360.

The previous prime is 21506378281. The next prime is 21506378297. The reversal of 21506378292 is 29287360512.

21506378292 is a `hidden beast` number, since 2 + 1 + 5 + 0 + 637 + 8 + 2 + 9 + 2 = 666.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21506378297) 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 47 ways as a sum of consecutive naturals, for example, 114423 + ... + 236865.

It is an arithmetic number, because the mean of its divisors is an integer number (467980968).

Almost surely, 2^21506378292 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 21506378292, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (33694629696).

21506378292 is an abundant number, since it is smaller than the sum of its proper divisors (45882881100).

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

21506378292 is a wasteful number, since it uses less digits than its factorization.

21506378292 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 122518 (or 122513 counting only the distinct ones).

The product of its (nonzero) digits is 362880, while the sum is 45.

The spelling of 21506378292 in words is "twenty-one billion, five hundred six million, three hundred seventy-eight thousand, two hundred ninety-two".