21020999 has 8 divisors (see below), whose sum is σ = 21364560. Its totient is φ = 20680000.

The previous prime is 21020971. The next prime is 21021001. The reversal of 21020999 is 99902012.

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 21020999 - 2¹² = 21016903 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21020299) 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, 21869 + ... + 22809.

It is an arithmetic number, because the mean of its divisors is an integer number (2670570).

Almost surely, 2^21020999 is an apocalyptic number.

21020999 is a deficient number, since it is larger than the sum of its proper divisors (343561).

21020999 is an equidigital number, since it uses as much as digits as its factorization.

21020999 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1281.

The product of its (nonzero) digits is 2916, while the sum is 32.

The square root of 21020999 is about 4584.8663012132. The cubic root of 21020999 is about 275.9843467633.

The spelling of 21020999 in words is "twenty-one million, twenty thousand, nine hundred ninety-nine".