21115776 has 64 divisors (see below), whose sum is σ = 61200000. Its totient is φ = 6397440.

The previous prime is 21115753. The next prime is 21115777. The reversal of 21115776 is 67751112.

It is a tau number, because it is divible by the number of its divisors (64).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21115777) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1725 + ... + 6723.

It is an arithmetic number, because the mean of its divisors is an integer number (956250).

Almost surely, 2^21115776 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 21115776, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (30600000).

21115776 is an abundant number, since it is smaller than the sum of its proper divisors (40084224).

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

21115776 is a wasteful number, since it uses less digits than its factorization.

21115776 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5027 (or 5015 counting only the distinct ones).

The product of its digits is 2940, while the sum is 30.

The square root of 21115776 is about 4595.1905292382. The cubic root of 21115776 is about 276.3985001765.

Adding to 21115776 its reverse (67751112), we get a palindrome (88866888).

It can be divided in two parts, 2111 and 5776, that added together give a palindrome (7887).

The spelling of 21115776 in words is "twenty-one million, one hundred fifteen thousand, seven hundred seventy-six".