21149538 has 8 divisors (see below), whose sum is σ = 42299088. Its totient is φ = 7049844.

The previous prime is 21149509. The next prime is 21149539. The reversal of 21149538 is 83594112.

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

21149538 is an admirable number.

It is a super-2 number, since 2×21149538² = 894605915226888, which contains 22 as substring.

It is a Smith number, since the sum of its digits (33) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a junction number, because it is equal to n+sod(n) for n = 21149499 and 21149508.

It is not an unprimeable number, because it can be changed into a prime (21149539) 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, 1762456 + ... + 1762467.

It is an arithmetic number, because the mean of its divisors is an integer number (5287386).

Almost surely, 2^21149538 is an apocalyptic number.

21149538 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.

21149538 is a wasteful number, since it uses less digits than its factorization.

21149538 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3524928.

The product of its digits is 8640, while the sum is 33.

The square root of 21149538 is about 4598.8626854908. The cubic root of 21149538 is about 276.5457328594.

The spelling of 21149538 in words is "twenty-one million, one hundred forty-nine thousand, five hundred thirty-eight".