21823561984 has 81 divisors (see below), whose sum is σ = 50712466287. Its totient is φ = 9345864192.

The previous prime is 21823561967. The next prime is 21823562011. The reversal of 21823561984 is 48916532812.

The square root of 21823561984 is 147728.

It is a perfect power (a square), and thus also a powerful number.

It is a super-3 number, since 3×21823561984³ (a number of 32 digits) contains 333 as substring.

It is a Harshad number since it is a multiple of its sum of digits (49).

It is an unprimeable number.

It is a polite number, since it can be written in 8 ways as a sum of consecutive naturals, for example, 16544877 + ... + 16546195.

Almost surely, 2^21823561984 is an apocalyptic number.

21823561984 is the 147728-th square number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21823561984

21823561984 is an abundant number, since it is smaller than the sum of its proper divisors (28888904303).

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

21823561984 is an frugal number, since it uses more digits than its factorization.

21823561984 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2668 (or 1328 counting only the distinct ones).

The product of its digits is 829440, while the sum is 49.

Multiplying 21823561984 by its sum of digits (49), we get a square (1069354537216 = 1034096²).

21823561984 divided by its sum of digits (49) gives a square (445378816 = 21104²).

The spelling of 21823561984 in words is "twenty-one billion, eight hundred twenty-three million, five hundred sixty-one thousand, nine hundred eighty-four".