21648138 has 32 divisors (see below), whose sum is σ = 44210880. Its totient is φ = 7065600.

The previous prime is 21648127. The next prime is 21648139. The reversal of 21648138 is 83184612.

It is a Curzon number.

It is a junction number, because it is equal to n+sod(n) for n = 21648099 and 21648108.

It is not an unprimeable number, because it can be changed into a prime (21648139) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 84106 + ... + 84362.

It is an arithmetic number, because the mean of its divisors is an integer number (1381590).

Almost surely, 2^21648138 is an apocalyptic number.

21648138 is an abundant number, since it is smaller than the sum of its proper divisors (22562742).

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

21648138 is a wasteful number, since it uses less digits than its factorization.

21648138 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 502.

The product of its digits is 9216, while the sum is 33.

The square root of 21648138 is about 4652.7559574944. The cubic root of 21648138 is about 278.7020624463.

The spelling of 21648138 in words is "twenty-one million, six hundred forty-eight thousand, one hundred thirty-eight".