21020828 has 12 divisors (see below), whose sum is σ = 37305072. Its totient is φ = 10362240.

The previous prime is 21020819. The next prime is 21020837. The reversal of 21020828 is 82802012.

It is an interprime number because it is at equal distance from previous prime (21020819) and next prime (21020837).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 36725 + ... + 37292.

It is an arithmetic number, because the mean of its divisors is an integer number (3108756).

Almost surely, 2^21020828 is an apocalyptic number.

It is an amenable number.

21020828 is a deficient number, since it is larger than the sum of its proper divisors (16284244).

21020828 is a wasteful number, since it uses less digits than its factorization.

21020828 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 74092 (or 74090 counting only the distinct ones).

The product of its (nonzero) digits is 512, while the sum is 23.

The square root of 21020828 is about 4584.8476528670. The cubic root of 21020828 is about 275.9835984092.

The spelling of 21020828 in words is "twenty-one million, twenty thousand, eight hundred twenty-eight".