21021683 has 2 divisors, whose sum is σ = 21021684. Its totient is φ = 21021682.

The previous prime is 21021667. The next prime is 21021697. The reversal of 21021683 is 38612012.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21021683 - 2⁴ = 21021667 is a prime.

It is a super-2 number, since 2×21021683² = 883822312304978, which contains 22 as substring.

It is a Sophie Germain prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (21021653) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10510841 + 10510842.

It is an arithmetic number, because the mean of its divisors is an integer number (10510842).

Almost surely, 2^21021683 is an apocalyptic number.

21021683 is a deficient number, since it is larger than the sum of its proper divisors (1).

21021683 is an equidigital number, since it uses as much as digits as its factorization.

21021683 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 576, while the sum is 23.

The square root of 21021683 is about 4584.9408938393. The cubic root of 21021683 is about 275.9873401390.

Adding to 21021683 its reverse (38612012), we get a palindrome (59633695).

The spelling of 21021683 in words is "twenty-one million, twenty-one thousand, six hundred eighty-three".