21394705 has 4 divisors (see below), whose sum is σ = 25673652. Its totient is φ = 17115760.

The previous prime is 21394697. The next prime is 21394733. The reversal of 21394705 is 50749312.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 14922769 + 6471936 = 3863^2 + 2544^2 .

It is not a de Polignac number, because 21394705 - 2³ = 21394697 is a prime.

It is a Duffinian number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2139466 + ... + 2139475.

It is an arithmetic number, because the mean of its divisors is an integer number (6418413).

Almost surely, 2^21394705 is an apocalyptic number.

It is an amenable number.

21394705 is a deficient number, since it is larger than the sum of its proper divisors (4278947).

21394705 is an equidigital number, since it uses as much as digits as its factorization.

21394705 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4278946.

The product of its (nonzero) digits is 7560, while the sum is 31.

The square root of 21394705 is about 4625.4410600504. The cubic root of 21394705 is about 277.6102097209.

The spelling of 21394705 in words is "twenty-one million, three hundred ninety-four thousand, seven hundred five".