21028245 has 32 divisors (see below), whose sum is σ = 38645760. Its totient is φ = 9564480.

The previous prime is 21028243. The next prime is 21028253. The reversal of 21028245 is 54282012.

It is not a de Polignac number, because 21028245 - 2¹ = 21028243 is a prime.

It is a congruent 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 31 ways as a sum of consecutive naturals, for example, 28086 + ... + 28824.

It is an arithmetic number, because the mean of its divisors is an integer number (1207680).

Almost surely, 2^21028245 is an apocalyptic number.

It is an amenable number.

21028245 is a deficient number, since it is larger than the sum of its proper divisors (17617515).

21028245 is a wasteful number, since it uses less digits than its factorization.

21028245 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1025.

The product of its (nonzero) digits is 1280, while the sum is 24.

The square root of 21028245 is about 4585.6564415577. The cubic root of 21028245 is about 276.0160539916.

The spelling of 21028245 in words is "twenty-one million, twenty-eight thousand, two hundred forty-five".