21422939 has 2 divisors, whose sum is σ = 21422940. Its totient is φ = 21422938.

The previous prime is 21422897. The next prime is 21422993. The reversal of 21422939 is 93922412.

Together with next prime (21422993) it forms an Ormiston pair, because they use the same digits, order apart.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21422939 - 2¹⁶ = 21357403 is a prime.

It is a Sophie Germain prime.

It is not a weakly prime, because it can be changed into another prime (21452939) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10711469 + 10711470.

It is an arithmetic number, because the mean of its divisors is an integer number (10711470).

Almost surely, 2^21422939 is an apocalyptic number.

21422939 is a deficient number, since it is larger than the sum of its proper divisors (1).

21422939 is an equidigital number, since it uses as much as digits as its factorization.

21422939 is an evil number, because the sum of its binary digits is even.

The product of its digits is 7776, while the sum is 32.

The square root of 21422939 is about 4628.4920870625. The cubic root of 21422939 is about 277.7322742115.

The spelling of 21422939 in words is "twenty-one million, four hundred twenty-two thousand, nine hundred thirty-nine".