21021043 has 2 divisors, whose sum is σ = 21021044. Its totient is φ = 21021042.

The previous prime is 21021001. The next prime is 21021047. The reversal of 21021043 is 34012012.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21021043 - 2¹³ = 21012851 is a prime.

It is not a weakly prime, because it can be changed into another prime (21021047) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10510521 + 10510522.

It is an arithmetic number, because the mean of its divisors is an integer number (10510522).

Almost surely, 2^21021043 is an apocalyptic number.

21021043 is a deficient number, since it is larger than the sum of its proper divisors (1).

21021043 is an equidigital number, since it uses as much as digits as its factorization.

21021043 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 48, while the sum is 13.

The square root of 21021043 is about 4584.8710996057. The cubic root of 21021043 is about 275.9845393216.

Adding to 21021043 its reverse (34012012), we get a palindrome (55033055).

The spelling of 21021043 in words is "twenty-one million, twenty-one thousand, forty-three".