21475688 has 32 divisors (see below), whose sum is σ = 44544360. Its totient is φ = 9642240.

The previous prime is 21475687. The next prime is 21475697. The reversal of 21475688 is 88657412.

It can be written as a sum of positive squares in 4 ways, for example, as 17322244 + 4153444 = 4162^2 + 2038^2 .

It is a super-2 number, since 2×21475688² = 922410350146688, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (21475687) 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, 1058 + ... + 6638.

Almost surely, 2^21475688 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 21475688, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (22272180).

21475688 is an abundant number, since it is smaller than the sum of its proper divisors (23068672).

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

21475688 is a wasteful number, since it uses less digits than its factorization.

21475688 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5637 (or 5633 counting only the distinct ones).

The product of its digits is 107520, while the sum is 41.

The square root of 21475688 is about 4634.1868758176. The cubic root of 21475688 is about 277.9600377317.

The spelling of 21475688 in words is "twenty-one million, four hundred seventy-five thousand, six hundred eighty-eight".