21216983 has 2 divisors, whose sum is σ = 21216984. Its totient is φ = 21216982.

The previous prime is 21216961. The next prime is 21216991. The reversal of 21216983 is 38961212.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21216983 - 2⁶ = 21216919 is a prime.

It is a Sophie Germain prime.

It is a Chen prime.

It is an alternating number because its digits alternate between even and odd.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21216883) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10608491 + 10608492.

It is an arithmetic number, because the mean of its divisors is an integer number (10608492).

Almost surely, 2^21216983 is an apocalyptic number.

21216983 is a deficient number, since it is larger than the sum of its proper divisors (1).

21216983 is an equidigital number, since it uses as much as digits as its factorization.

21216983 is an evil number, because the sum of its binary digits is even.

The product of its digits is 5184, while the sum is 32.

The square root of 21216983 is about 4606.1896400387. The cubic root of 21216983 is about 276.8393852248.

The spelling of 21216983 in words is "twenty-one million, two hundred sixteen thousand, nine hundred eighty-three".