21675438 has 40 divisors (see below), whose sum is σ = 49318632. Its totient is φ = 7113744.

The previous prime is 21675427. The next prime is 21675449. The reversal of 21675438 is 83457612.

21675438 is a `hidden beast` number, since 216 + 7 + 5 + 438 = 666.

It is an interprime number because it is at equal distance from previous prime (21675427) and next prime (21675449).

It is a super-2 number, since 2×21675438² = 939649224983688, which contains 22 as substring.

It is a Curzon number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 19 ways as a sum of consecutive naturals, for example, 9856 + ... + 11852.

Almost surely, 2^21675438 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21675438, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (24659316).

21675438 is an abundant number, since it is smaller than the sum of its proper divisors (27643194).

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

21675438 is a wasteful number, since it uses less digits than its factorization.

21675438 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2078 (or 2069 counting only the distinct ones).

The product of its digits is 40320, while the sum is 36.

The square root of 21675438 is about 4655.6887782583. The cubic root of 21675438 is about 278.8191682872.

The spelling of 21675438 in words is "twenty-one million, six hundred seventy-five thousand, four hundred thirty-eight".