21090917952 has 336 divisors, whose sum is σ = 68799098368. Its totient is φ = 6131220480.

The previous prime is 21090917951. The next prime is 21090917963. The reversal of 21090917952 is 25971909012.

It is a junction number, because it is equal to n+sod(n) for n = 21090917898 and 21090917907.

It is not an unprimeable number, because it can be changed into a prime (21090917951) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 9980448 + ... + 9982560.

Almost surely, 2^21090917952 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 21090917952, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (34399549184).

21090917952 is an abundant number, since it is smaller than the sum of its proper divisors (47708180416).

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

21090917952 is a wasteful number, since it uses less digits than its factorization.

21090917952 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2218 (or 2205 counting only the distinct ones).

The product of its (nonzero) digits is 102060, while the sum is 45.

The spelling of 21090917952 in words is "twenty-one billion, ninety million, nine hundred seventeen thousand, nine hundred fifty-two".