21643469 has 4 divisors (see below), whose sum is σ = 21661920. Its totient is φ = 21625020.

The previous prime is 21643429. The next prime is 21643507. The reversal of 21643469 is 96434612.

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 a de Polignac number, because none of the positive numbers 2^k-21643469 is a prime.

It is a super-2 number, since 2×21643469² = 936879500707922, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21643429) 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, 7337 + ... + 9854.

It is an arithmetic number, because the mean of its divisors is an integer number (5415480).

Almost surely, 2^21643469 is an apocalyptic number.

It is an amenable number.

21643469 is a deficient number, since it is larger than the sum of its proper divisors (18451).

21643469 is a wasteful number, since it uses less digits than its factorization.

21643469 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 18450.

The product of its digits is 31104, while the sum is 35.

The square root of 21643469 is about 4652.2541848012. The cubic root of 21643469 is about 278.6820244875.

The spelling of 21643469 in words is "twenty-one million, six hundred forty-three thousand, four hundred sixty-nine".