21603138 has 8 divisors (see below), whose sum is σ = 43206288. Its totient is φ = 7201044.

The previous prime is 21603137. The next prime is 21603139. The reversal of 21603138 is 83130612.

It is an interprime number because it is at equal distance from previous prime (21603137) and next prime (21603139).

It is a sphenic number, since it is the product of 3 distinct primes.

21603138 is an admirable number.

It is a Smith number, since the sum of its digits (24) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (21603137) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1800256 + ... + 1800267.

It is an arithmetic number, because the mean of its divisors is an integer number (5400786).

Almost surely, 2^21603138 is an apocalyptic number.

21603138 is a primitive abundant number, since it is smaller than the sum of its proper divisors, none of which is abundant.

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

21603138 is a wasteful number, since it uses less digits than its factorization.

21603138 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3600528.

The product of its (nonzero) digits is 864, while the sum is 24.

The square root of 21603138 is about 4647.9175982369. The cubic root of 21603138 is about 278.5088157580.

The spelling of 21603138 in words is "twenty-one million, six hundred three thousand, one hundred thirty-eight".