21673253 has 4 divisors (see below), whose sum is σ = 24769440. Its totient is φ = 18577068.

The previous prime is 21673241. The next prime is 21673259. The reversal of 21673253 is 35237612.

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.

It is a cyclic number.

It is not a de Polignac number, because 21673253 - 2⁸ = 21672997 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21673259) 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, 1548083 + ... + 1548096.

It is an arithmetic number, because the mean of its divisors is an integer number (6192360).

Almost surely, 2^21673253 is an apocalyptic number.

It is an amenable number.

21673253 is a deficient number, since it is larger than the sum of its proper divisors (3096187).

21673253 is an equidigital number, since it uses as much as digits as its factorization.

21673253 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3096186.

The product of its digits is 7560, while the sum is 29.

The square root of 21673253 is about 4655.4541131881. The cubic root of 21673253 is about 278.8097991515.

The spelling of 21673253 in words is "twenty-one million, six hundred seventy-three thousand, two hundred fifty-three".