21210993 has 12 divisors (see below), whose sum is σ = 30706000. Its totient is φ = 14109336.

The previous prime is 21210989. The next prime is 21211009. The reversal of 21210993 is 39901212.

It is not a de Polignac number, because 21210993 - 2² = 21210989 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21210193) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 2130 + ... + 6852.

Almost surely, 2^21210993 is an apocalyptic number.

It is an amenable number.

21210993 is a deficient number, since it is larger than the sum of its proper divisors (9495007).

21210993 is a wasteful number, since it uses less digits than its factorization.

21210993 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5228 (or 5225 counting only the distinct ones).

The product of its (nonzero) digits is 972, while the sum is 27.

The square root of 21210993 is about 4605.5393820920. The cubic root of 21210993 is about 276.8133302481.

The spelling of 21210993 in words is "twenty-one million, two hundred ten thousand, nine hundred ninety-three".