21020798 has 4 divisors (see below), whose sum is σ = 31531200. Its totient is φ = 10510398.

The previous prime is 21020777. The next prime is 21020803. The reversal of 21020798 is 89702012.

It is a happy number.

It is a semiprime because it is the product of two primes.

It is a self number, because there is not a number n which added to its sum of digits gives 21020798.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5255198 + ... + 5255201.

It is an arithmetic number, because the mean of its divisors is an integer number (7882800).

Almost surely, 2^21020798 is an apocalyptic number.

21020798 is a deficient number, since it is larger than the sum of its proper divisors (10510402).

21020798 is a wasteful number, since it uses less digits than its factorization.

21020798 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10510401.

The product of its (nonzero) digits is 2016, while the sum is 29.

The square root of 21020798 is about 4584.8443812195. The cubic root of 21020798 is about 275.9834671186.

The spelling of 21020798 in words is "twenty-one million, twenty thousand, seven hundred ninety-eight".