21989772 has 192 divisors, whose sum is σ = 72576000. Its totient is φ = 5612544.

The previous prime is 21989761. The next prime is 21989777. The reversal of 21989772 is 27798912.

It is a super-2 number, since 2×21989772² = 967100145223968, which contains 22 as substring.

It is a hoax number, since the sum of its digits (45) coincides with the sum of the digits of its distinct prime factors.

It is not an unprimeable number, because it can be changed into a prime (21989777) by changing a digit.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 372679 + ... + 372737.

It is an arithmetic number, because the mean of its divisors is an integer number (378000).

Almost surely, 2^21989772 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 21989772, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (36288000).

21989772 is an abundant number, since it is smaller than the sum of its proper divisors (50586228).

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

21989772 is a wasteful number, since it uses less digits than its factorization.

21989772 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 125 (or 117 counting only the distinct ones).

The product of its digits is 127008, while the sum is 45.

The square root of 21989772 is about 4689.3253246069. The cubic root of 21989772 is about 280.1605032159.

The spelling of 21989772 in words is "twenty-one million, nine hundred eighty-nine thousand, seven hundred seventy-two".