21028249 has 8 divisors (see below), whose sum is σ = 23329440. Its totient is φ = 18792000.

The previous prime is 21028243. The next prime is 21028253. The reversal of 21028249 is 94282012.

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

It is a cyclic number.

It is not a de Polignac number, because 21028249 - 2¹³ = 21020057 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21028243) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 15552 + ... + 16849.

It is an arithmetic number, because the mean of its divisors is an integer number (2916180).

Almost surely, 2^21028249 is an apocalyptic number.

It is an amenable number.

21028249 is a deficient number, since it is larger than the sum of its proper divisors (2301191).

21028249 is a wasteful number, since it uses less digits than its factorization.

21028249 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 32471.

The product of its (nonzero) digits is 2304, while the sum is 28.

The square root of 21028249 is about 4585.6568777003. The cubic root of 21028249 is about 276.0160714929.

It can be divided in two parts, 210 and 28249, that multiplied together give a triangular number (5932290 = T₃₄₄₄).

The spelling of 21028249 in words is "twenty-one million, twenty-eight thousand, two hundred forty-nine".