21024261 has 18 divisors (see below), whose sum is σ = 30805970. Its totient is φ = 13816800.

The previous prime is 21024259. The next prime is 21024271. The reversal of 21024261 is 16242012.

It can be written as a sum of positive squares in 3 ways, for example, as 18792225 + 2232036 = 4335^2 + 1494^2 .

It is not a de Polignac number, because 21024261 - 2¹ = 21024259 is a prime.

It is a super-2 number, since 2×21024261² = 884039101192242, which contains 22 as substring.

It is a hoax number, since the sum of its digits (18) coincides with the sum of the digits of its distinct prime factors.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21024221) by changing a digit.

It is a polite number, since it can be written in 17 ways as a sum of consecutive naturals, for example, 91695 + ... + 91923.

Almost surely, 2^21024261 is an apocalyptic number.

It is an amenable number.

21024261 is a deficient number, since it is larger than the sum of its proper divisors (9781709).

21024261 is a wasteful number, since it uses less digits than its factorization.

21024261 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 437 (or 333 counting only the distinct ones).

The product of its (nonzero) digits is 192, while the sum is 18.

The square root of 21024261 is about 4585.2220229777. Note that the first 3 decimals coincide. The cubic root of 21024261 is about 275.9986216062.

Adding to 21024261 its reverse (16242012), we get a palindrome (37266273).

The spelling of 21024261 in words is "twenty-one million, twenty-four thousand, two hundred sixty-one".