21953774556 has 144 divisors (see below), whose sum is σ = 67065643008. Its totient is φ = 5922028800.

The previous prime is 21953774539. The next prime is 21953774611. The reversal of 21953774556 is 65547735912.

It is a happy number.

21953774556 is a `hidden beast` number, since 2 + 19 + 5 + 3 + 7 + 74 + 556 = 666.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 286021 + ... + 354563.

It is an arithmetic number, because the mean of its divisors is an integer number (465733632).

Almost surely, 2^21953774556 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 21953774556, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (33532821504).

21953774556 is an abundant number, since it is smaller than the sum of its proper divisors (45111868452).

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

21953774556 is a wasteful number, since it uses less digits than its factorization.

21953774556 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 68632 (or 68627 counting only the distinct ones).

The product of its digits is 7938000, while the sum is 54.

The spelling of 21953774556 in words is "twenty-one billion, nine hundred fifty-three million, seven hundred seventy-four thousand, five hundred fifty-six".