21434939 has 2 divisors, whose sum is σ = 21434940. Its totient is φ = 21434938.

The previous prime is 21434921. The next prime is 21434953. The reversal of 21434939 is 93943412.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21434939 - 2²⁰ = 20386363 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21434899 and 21434908.

It is not a weakly prime, because it can be changed into another prime (21434639) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10717469 + 10717470.

It is an arithmetic number, because the mean of its divisors is an integer number (10717470).

Almost surely, 2^21434939 is an apocalyptic number.

21434939 is a deficient number, since it is larger than the sum of its proper divisors (1).

21434939 is an equidigital number, since it uses as much as digits as its factorization.

21434939 is an evil number, because the sum of its binary digits is even.

The product of its digits is 23328, while the sum is 35.

The square root of 21434939 is about 4629.7882240984. The cubic root of 21434939 is about 277.7841215203.

It can be divided in two parts, 214 and 34939, that added together give a palindrome (35153).

The spelling of 21434939 in words is "twenty-one million, four hundred thirty-four thousand, nine hundred thirty-nine".