21261673 has 4 divisors (see below), whose sum is σ = 21270928. Its totient is φ = 21252420.

The previous prime is 21261671. The next prime is 21261677. The reversal of 21261673 is 37616212.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also a brilliant number, because the two primes have the same length.

It is a cyclic number.

It is not a de Polignac number, because 21261673 - 2¹ = 21261671 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21261671) 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, 1738 + ... + 6748.

It is an arithmetic number, because the mean of its divisors is an integer number (5317732).

Almost surely, 2^21261673 is an apocalyptic number.

It is an amenable number.

21261673 is a deficient number, since it is larger than the sum of its proper divisors (9255).

21261673 is an equidigital number, since it uses as much as digits as its factorization.

21261673 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9254.

The product of its digits is 3024, while the sum is 28.

The square root of 21261673 is about 4611.0381694365. The cubic root of 21261673 is about 277.0336207546.

Adding to 21261673 its reverse (37616212), we get a palindrome (58877885).

The spelling of 21261673 in words is "twenty-one million, two hundred sixty-one thousand, six hundred seventy-three".