21768396 has 48 divisors (see below), whose sum is σ = 57087744. Its totient is φ = 6405696.

The previous prime is 21768391. The next prime is 21768407. The reversal of 21768396 is 69386712.

It is a happy number.

It is not an unprimeable number, because it can be changed into a prime (21768391) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 555 + ... + 6621.

It is an arithmetic number, because the mean of its divisors is an integer number (1189328).

Almost surely, 2^21768396 is an apocalyptic number.

21768396 is a gapful number since it is divisible by the number (26) 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 21768396, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (28543872).

21768396 is an abundant number, since it is smaller than the sum of its proper divisors (35319348).

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

21768396 is a wasteful number, since it uses less digits than its factorization.

21768396 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6110 (or 6108 counting only the distinct ones).

The product of its digits is 108864, while the sum is 42.

The square root of 21768396 is about 4665.6613679092. The cubic root of 21768396 is about 279.2171842145.

The spelling of 21768396 in words is "twenty-one million, seven hundred sixty-eight thousand, three hundred ninety-six".