21778488 has 48 divisors (see below), whose sum is σ = 59459400. Its totient is φ = 7200960.

The previous prime is 21778481. The next prime is 21778489. The reversal of 21778488 is 88487712.

It is a super-2 number, since 2×21778488² = 948605079132288, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21778481) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 8278 + ... + 10586.

Almost surely, 2^21778488 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 21778488, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (29729700).

21778488 is an abundant number, since it is smaller than the sum of its proper divisors (37680912).

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

21778488 is a wasteful number, since it uses less digits than its factorization.

21778488 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2452 (or 2445 counting only the distinct ones).

The product of its digits is 200704, while the sum is 45.

The square root of 21778488 is about 4666.7427612844. The cubic root of 21778488 is about 279.2603266441.

The spelling of 21778488 in words is "twenty-one million, seven hundred seventy-eight thousand, four hundred eighty-eight".