21049705 has 8 divisors (see below), whose sum is σ = 25292232. Its totient is φ = 16818048.

The previous prime is 21049703. The next prime is 21049709. The reversal of 21049705 is 50794012.

It is a happy number.

It can be written as a sum of positive squares in 4 ways, for example, as 3308761 + 17740944 = 1819^2 + 4212^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 21049705 - 2¹ = 21049703 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21049703) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 2439 + ... + 6931.

It is an arithmetic number, because the mean of its divisors is an integer number (3161529).

Almost surely, 2^21049705 is an apocalyptic number.

It is an amenable number.

21049705 is a deficient number, since it is larger than the sum of its proper divisors (4242527).

21049705 is an equidigital number, since it uses as much as digits as its factorization.

21049705 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5435.

The product of its (nonzero) digits is 2520, while the sum is 28.

The square root of 21049705 is about 4587.9957497801. The cubic root of 21049705 is about 276.1099164876.

The spelling of 21049705 in words is "twenty-one million, forty-nine thousand, seven hundred five".