21008741 has 4 divisors (see below), whose sum is σ = 22624812. Its totient is φ = 19392672.

The previous prime is 21008681. The next prime is 21008749. The reversal of 21008741 is 14780012.

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 11730625 + 9278116 = 3425^2 + 3046^2 .

It is not a de Polignac number, because 21008741 - 2⁶ = 21008677 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21008749) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 808016 + ... + 808041.

It is an arithmetic number, because the mean of its divisors is an integer number (5656203).

Almost surely, 2^21008741 is an apocalyptic number.

It is an amenable number.

21008741 is a deficient number, since it is larger than the sum of its proper divisors (1616071).

21008741 is a wasteful number, since it uses less digits than its factorization.

21008741 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1616070.

The product of its (nonzero) digits is 448, while the sum is 23.

The square root of 21008741 is about 4583.5293170220. The cubic root of 21008741 is about 275.9306913064.

Adding to 21008741 its reverse (14780012), we get a palindrome (35788753).

The spelling of 21008741 in words is "twenty-one million, eight thousand, seven hundred forty-one".