21835421 has 4 divisors (see below), whose sum is σ = 21885600. Its totient is φ = 21785244.

The previous prime is 21835393. The next prime is 21835447. The reversal of 21835421 is 12453812.

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-21835421 is a prime.

It is a super-2 number, since 2×21835421² = 953571220494482, 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 (21835481) 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, 24431 + ... + 25308.

It is an arithmetic number, because the mean of its divisors is an integer number (5471400).

Almost surely, 2^21835421 is an apocalyptic number.

It is an amenable number.

21835421 is a deficient number, since it is larger than the sum of its proper divisors (50179).

21835421 is an equidigital number, since it uses as much as digits as its factorization.

21835421 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 50178.

The product of its digits is 1920, while the sum is 26.

The square root of 21835421 is about 4672.8386447640. The cubic root of 21835421 is about 279.5034609676.

The spelling of 21835421 in words is "twenty-one million, eight hundred thirty-five thousand, four hundred twenty-one".