21117744 has 60 divisors (see below), whose sum is σ = 60237216. Its totient is φ = 6903936.

The previous prime is 21117739. The next prime is 21117751. The reversal of 21117744 is 44771112.

It is a super-2 number, since 2×21117744² = 891918223299072, which contains 22 as substring.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 6249 + ... + 9015.

Almost surely, 2^21117744 is an apocalyptic number.

21117744 is a gapful number since it is divisible by the number (24) 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 21117744, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (30118608).

21117744 is an abundant number, since it is smaller than the sum of its proper divisors (39119472).

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

21117744 is a wasteful number, since it uses less digits than its factorization.

21117744 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2834 (or 2825 counting only the distinct ones).

The product of its digits is 1568, while the sum is 27.

The square root of 21117744 is about 4595.4046611806. The cubic root of 21117744 is about 276.4070867321.

Adding to 21117744 its reverse (44771112), we get a palindrome (65888856).

It can be divided in two parts, 211 and 17744, that added together give a triangular number (17955 = T₁₈₉).

The spelling of 21117744 in words is "twenty-one million, one hundred seventeen thousand, seven hundred forty-four".