21478128 has 80 divisors (see below), whose sum is σ = 64162560. Its totient is φ = 6064128.

The previous prime is 21478117. The next prime is 21478147. The reversal of 21478128 is 82187412.

It is a happy number.

It is a super-2 number, since 2×21478128² = 922619964768768, which contains 22 as substring.

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

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 32263 + ... + 32921.

It is an arithmetic number, because the mean of its divisors is an integer number (802032).

Almost surely, 2^21478128 is an apocalyptic number.

21478128 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 21478128, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (32081280).

21478128 is an abundant number, since it is smaller than the sum of its proper divisors (42684432).

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

21478128 is a wasteful number, since it uses less digits than its factorization.

21478128 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 774 (or 768 counting only the distinct ones).

The product of its digits is 7168, while the sum is 33.

The square root of 21478128 is about 4634.4501291955. The cubic root of 21478128 is about 277.9705643143.

The spelling of 21478128 in words is "twenty-one million, four hundred seventy-eight thousand, one hundred twenty-eight".