21049481 has 4 divisors (see below), whose sum is σ = 21075012. Its totient is φ = 21023952.

The previous prime is 21049387. The next prime is 21049493. The reversal of 21049481 is 18494012.

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 8904256 + 12145225 = 2984^2 + 3485^2 .

It is a cyclic number.

It is not a de Polignac number, because 21049481 - 2¹⁸ = 20787337 is a prime.

It is a super-2 number, since 2×21049481² = 886161300738722, which contains 22 as substring.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (21049681) 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, 11486 + ... + 13191.

It is an arithmetic number, because the mean of its divisors is an integer number (5268753).

Almost surely, 2^21049481 is an apocalyptic number.

It is an amenable number.

21049481 is a deficient number, since it is larger than the sum of its proper divisors (25531).

21049481 is an equidigital number, since it uses as much as digits as its factorization.

21049481 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 25530.

The product of its (nonzero) digits is 2304, while the sum is 29.

The square root of 21049481 is about 4587.9713381842. The cubic root of 21049481 is about 276.1089370781.

The spelling of 21049481 in words is "twenty-one million, forty-nine thousand, four hundred eighty-one".