21779472 has 160 divisors (see below), whose sum is σ = 69995520. Its totient is φ = 5736960.

The previous prime is 21779447. The next prime is 21779473. The reversal of 21779472 is 27497712.

It is a Harshad number since it is a multiple of its sum of digits (39).

It is a self number, because there is not a number n which added to its sum of digits gives 21779472.

It is not an unprimeable number, because it can be changed into a prime (21779473) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 130333 + ... + 130499.

It is an arithmetic number, because the mean of its divisors is an integer number (437472).

Almost surely, 2^21779472 is an apocalyptic number.

21779472 is a gapful number since it is divisible by the number (22) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21779472, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (34997760).

21779472 is an abundant number, since it is smaller than the sum of its proper divisors (48216048).

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

21779472 is a wasteful number, since it uses less digits than its factorization.

21779472 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 221 (or 215 counting only the distinct ones).

The product of its digits is 49392, while the sum is 39.

The square root of 21779472 is about 4666.8481869459. The cubic root of 21779472 is about 279.2645324460.

The spelling of 21779472 in words is "twenty-one million, seven hundred seventy-nine thousand, four hundred seventy-two".