21187038 has 8 divisors (see below), whose sum is σ = 42374088. Its totient is φ = 7062344.

The previous prime is 21187027. The next prime is 21187063. The reversal of 21187038 is 83078112.

It is a happy number.

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

21187038 is an admirable number.

It is a junction number, because it is equal to n+sod(n) for n = 21186996 and 21187014.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1765581 + ... + 1765592.

It is an arithmetic number, because the mean of its divisors is an integer number (5296761).

Almost surely, 2^21187038 is an apocalyptic number.

21187038 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.

21187038 is a wasteful number, since it uses less digits than its factorization.

21187038 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3531178.

The product of its (nonzero) digits is 2688, while the sum is 30.

The square root of 21187038 is about 4602.9379748157. The cubic root of 21187038 is about 276.7090830275.

It can be divided in two parts, 2118703 and 8, that added together give a triangular number (2118711 = T₂₀₅₈).

The spelling of 21187038 in words is "twenty-one million, one hundred eighty-seven thousand, thirty-eight".