21028398 has 16 divisors (see below), whose sum is σ = 42154320. Its totient is φ = 6993216.

The previous prime is 21028391. The next prime is 21028409. The reversal of 21028398 is 89382012.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21028391) 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, 1093 + ... + 6576.

It is an arithmetic number, because the mean of its divisors is an integer number (2634645).

Almost surely, 2^21028398 is an apocalyptic number.

21028398 is an abundant number, since it is smaller than the sum of its proper divisors (21125922).

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

21028398 is a wasteful number, since it uses less digits than its factorization.

21028398 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8131.

The product of its (nonzero) digits is 6912, while the sum is 33.

The square root of 21028398 is about 4585.6731239808. The cubic root of 21028398 is about 276.0167234143.

The spelling of 21028398 in words is "twenty-one million, twenty-eight thousand, three hundred ninety-eight".