21248461 has 4 divisors (see below), whose sum is σ = 22882972. Its totient is φ = 19613952.

The previous prime is 21248431. The next prime is 21248473. The reversal of 21248461 is 16484212.

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 2499561 + 18748900 = 1581^2 + 4330^2 .

It is a cyclic number.

It is not a de Polignac number, because 21248461 - 2⁵ = 21248429 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 (21248401) 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, 817236 + ... + 817261.

It is an arithmetic number, because the mean of its divisors is an integer number (5720743).

Almost surely, 2^21248461 is an apocalyptic number.

It is an amenable number.

21248461 is a deficient number, since it is larger than the sum of its proper divisors (1634511).

21248461 is a wasteful number, since it uses less digits than its factorization.

21248461 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1634510.

The product of its digits is 3072, while the sum is 28.

The square root of 21248461 is about 4609.6052976367. The cubic root of 21248461 is about 276.9762259829.

It can be divided in two parts, 2124 and 8461, that added together give a triangular number (10585 = T₁₄₅).

The spelling of 21248461 in words is "twenty-one million, two hundred forty-eight thousand, four hundred sixty-one".