21168624 has 60 divisors (see below), whose sum is σ = 56091896. Its totient is φ = 6878976.

The previous prime is 21168619. The next prime is 21168649. The reversal of 21168624 is 42686112.

It is a super-2 number, since 2×21168624² = 896221284106752, which contains 22 as substring.

It is a nude number because it is divisible by every one of its digits.

It is a junction number, because it is equal to n+sod(n) for n = 21168591 and 21168600.

It is a congruent number.

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, 134754 + ... + 134910.

Almost surely, 2^21168624 is an apocalyptic number.

21168624 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 21168624, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (28045948).

21168624 is an abundant number, since it is smaller than the sum of its proper divisors (34923272).

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

21168624 is a wasteful number, since it uses less digits than its factorization.

With its successor (21168625) it forms a Ruth-Aaron pair, since the sum of their prime factors is the same (274).

21168624 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 274 (or 215 counting only the distinct ones).

The product of its digits is 4608, while the sum is 30.

The square root of 21168624 is about 4600.9372958127. The cubic root of 21168624 is about 276.6288956679.

The spelling of 21168624 in words is "twenty-one million, one hundred sixty-eight thousand, six hundred twenty-four".