21254839 has 2 divisors, whose sum is σ = 21254840. Its totient is φ = 21254838.

The previous prime is 21254819. The next prime is 21254861. The reversal of 21254839 is 93845212.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21254839 - 2⁹ = 21254327 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21254819) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10627419 + 10627420.

It is an arithmetic number, because the mean of its divisors is an integer number (10627420).

Almost surely, 2^21254839 is an apocalyptic number.

21254839 is a deficient number, since it is larger than the sum of its proper divisors (1).

21254839 is an equidigital number, since it uses as much as digits as its factorization.

21254839 is an evil number, because the sum of its binary digits is even.

The product of its digits is 17280, while the sum is 34.

The square root of 21254839 is about 4610.2970620124. The cubic root of 21254839 is about 277.0039358744.

The spelling of 21254839 in words is "twenty-one million, two hundred fifty-four thousand, eight hundred thirty-nine".