21047465 has 4 divisors (see below), whose sum is σ = 25256964. Its totient is φ = 16837968.

The previous prime is 21047449. The next prime is 21047527. The reversal of 21047465 is 56474012.

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 13719616 + 7327849 = 3704^2 + 2707^2 .

It is a cyclic number.

It is not a de Polignac number, because 21047465 - 2⁴ = 21047449 is a prime.

It is a Duffinian number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2104742 + ... + 2104751.

It is an arithmetic number, because the mean of its divisors is an integer number (6314241).

Almost surely, 2^21047465 is an apocalyptic number.

It is an amenable number.

21047465 is a deficient number, since it is larger than the sum of its proper divisors (4209499).

21047465 is an equidigital number, since it uses as much as digits as its factorization.

21047465 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4209498.

The product of its (nonzero) digits is 6720, while the sum is 29.

The square root of 21047465 is about 4587.7516279764. The cubic root of 21047465 is about 276.1001220803.

It can be divided in two parts, 21047 and 465, that added together give a palindrome (21512).

The spelling of 21047465 in words is "twenty-one million, forty-seven thousand, four hundred sixty-five".