21554315216 has 120 divisors (see below), whose sum is σ = 49622661000. Its totient is φ = 9041227776.

The previous prime is 21554315201. The next prime is 21554315261. The reversal of 21554315216 is 61251345512.

It can be written as a sum of positive squares in 4 ways, for example, as 1361905216 + 20192410000 = 36904^2 + 142100^2 .

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 7839410 + ... + 7842158.

It is an arithmetic number, because the mean of its divisors is an integer number (413522175).

Almost surely, 2^21554315216 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 21554315216, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (24811330500).

21554315216 is an abundant number, since it is smaller than the sum of its proper divisors (28068345784).

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

21554315216 is a wasteful number, since it uses less digits than its factorization.

21554315216 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2981 (or 2968 counting only the distinct ones).

The product of its digits is 36000, while the sum is 35.

The spelling of 21554315216 in words is "twenty-one billion, five hundred fifty-four million, three hundred fifteen thousand, two hundred sixteen".