21464688 has 80 divisors (see below), whose sum is σ = 63892736. Its totient is φ = 6082560.

The previous prime is 21464687. The next prime is 21464711. The reversal of 21464688 is 88646412.

It is a Cunningham number, because it is equal to 4633²-1.

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

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21464683) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 64683 + ... + 65013.

Almost surely, 2^21464688 is an apocalyptic number.

21464688 is a gapful number since it is divisible by the number (28) 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 21464688, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (31946368).

21464688 is an abundant number, since it is smaller than the sum of its proper divisors (42428048).

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

21464688 is a wasteful number, since it uses less digits than its factorization.

21464688 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 542 (or 536 counting only the distinct ones).

The product of its digits is 73728, while the sum is 39.

The square root of 21464688 is about 4632.9998920786. Note that the first 3 decimals coincide. The cubic root of 21464688 is about 277.9125719245.

The spelling of 21464688 in words is "twenty-one million, four hundred sixty-four thousand, six hundred eighty-eight".