21351566448 has 480 divisors, whose sum is σ = 68189921280. Its totient is φ = 6209280000.

The previous prime is 21351566413. The next prime is 21351566461. The reversal of 21351566448 is 84466515312.

21351566448 is a `hidden beast` number, since 2 + 135 + 15 + 66 + 448 = 666.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 95 ways as a sum of consecutive naturals, for example, 211401598 + ... + 211401698.

It is an arithmetic number, because the mean of its divisors is an integer number (142062336).

Almost surely, 2^21351566448 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 21351566448, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (34094960640).

21351566448 is an abundant number, since it is smaller than the sum of its proper divisors (46838354832).

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

21351566448 is a wasteful number, since it uses less digits than its factorization.

21351566448 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 269 (or 260 counting only the distinct ones).

The product of its digits is 691200, while the sum is 45.

The spelling of 21351566448 in words is "twenty-one billion, three hundred fifty-one million, five hundred sixty-six thousand, four hundred forty-eight".